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1.
Orphanet J Rare Dis ; 19(1): 327, 2024 Sep 06.
Artículo en Inglés | MEDLINE | ID: mdl-39243101

RESUMEN

The diagnostic odysseys for rare disease patients are getting shorter as next-generation sequencing becomes more widespread. However, the complex genetic diversity and factors influencing expressivity continue to challenge accurate diagnosis, leaving more than 50% of genetic variants categorized as variants of uncertain significance.Genomic expression intricately hinges on localized interactions among its products. Conventional variant prioritization, biased towards known disease genes and the structure-function paradigm, overlooks the potential impact of variants shaping the composition, location, size, and properties of biomolecular condensates, genuine membraneless organelles swiftly sensing and responding to environmental changes, and modulating expressivity.To address this complexity, we propose to focus on the nexus of genetic variants within biomolecular condensates determinants. Scrutinizing variant effects in these membraneless organelles could refine prioritization, enhance diagnostics, and unveil the molecular underpinnings of rare diseases. Integrating comprehensive genome sequencing, transcriptomics, and computational models can unravel variant pathogenicity and disease mechanisms, enabling precision medicine. This paper presents the rationale driving our proposal and describes a protocol to implement this approach. By fusing state-of-the-art knowledge and methodologies into the clinical practice, we aim to redefine rare diseases diagnosis, leveraging the power of scientific advancement for more informed medical decisions.


Asunto(s)
Enfermedades Raras , Humanos , Variación Genética/genética , Secuenciación de Nucleótidos de Alto Rendimiento , Enfermedades Raras/diagnóstico , Enfermedades Raras/genética
2.
ACS Nano ; 2024 Sep 14.
Artículo en Inglés | MEDLINE | ID: mdl-39276130

RESUMEN

Intrinsically disordered proteins (IDPs) are emerging therapeutic targets for human diseases. However, probing their transient conformations remains challenging because of conformational heterogeneity. To address this problem, we developed a biosensor using a point-functionalized silicon nanowire (SiNW) that allows for real-time sampling of single-molecule dynamics. A single IDP, N-terminal transactivation domain of tumor suppressor protein p53 (p53TAD1), was covalently conjugated to the SiNW through chemical engineering, and its conformational transition dynamics was characterized as current fluctuations. Furthermore, when a globular protein ligand in solution bound to the targeted p53TAD1, protein-protein interactions could be unambiguously distinguished from large-amplitude current signals. These proof-of-concept experiments enable semiquantitative, realistic characterization of the structural properties of IDPs and constitute the basis for developing a valuable tool for protein profiling and drug discovery in the future.

3.
Biophys Chem ; 314: 107319, 2024 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-39232485

RESUMEN

The aggregation of the protein α-synuclein into amyloid deposits is associated with multiple neurological disorders, including Parkinson's disease. Soluble amyloid oligomers are reported to exhibit higher toxicity than insoluble amyloid fibrils, with dimers being the smallest toxic oligomer. Small molecule drugs, such as fasudil, have shown potential in targeting α-synuclein aggregation and reducing its toxicity. In this study, we use atomistic molecular dynamics simulations to demonstrate how fasudil affects the earliest stage of aggregation, namely dimerization. Our results show that the presence of fasudil reduces the propensity for intermolecular contact formation between protein chains. Consistent with previous reports, our analysis confirms that fasudil predominantly interacts with the negatively charged C-terminal region of α-synuclein. However, we also observe transient interactions with residues in the charged N-terminal and hydrophobic NAC regions. Our simulations indicate that while fasudil prominently interacts with the C-terminal region, it is the transient interactions with residues in the N-terminal and NAC regions that effectively block the formation of intermolecular contacts between protein chains and prevent early dimerization of this disordered protein.


Asunto(s)
1-(5-Isoquinolinesulfonil)-2-Metilpiperazina , Simulación de Dinámica Molecular , Multimerización de Proteína , alfa-Sinucleína , alfa-Sinucleína/química , alfa-Sinucleína/metabolismo , 1-(5-Isoquinolinesulfonil)-2-Metilpiperazina/análogos & derivados , 1-(5-Isoquinolinesulfonil)-2-Metilpiperazina/farmacología , 1-(5-Isoquinolinesulfonil)-2-Metilpiperazina/química , Humanos , Multimerización de Proteína/efectos de los fármacos , Agregado de Proteínas/efectos de los fármacos
4.
Proc Natl Acad Sci U S A ; 121(37): e2408104121, 2024 Sep 10.
Artículo en Inglés | MEDLINE | ID: mdl-39231207

RESUMEN

Prolyl-hydroxylation is an oxygen-dependent posttranslational modification (PTM) that is known to regulate fibril formation of collagenous proteins and modulate cellular expression of hypoxia-inducible factor (HIF) α subunits. However, our understanding of this important but relatively rare PTM has remained incomplete due to the lack of biophysical methodologies that can directly measure multiple prolyl-hydroxylation events within intrinsically disordered proteins. Here, we describe a real-time 13C-direct detection NMR-based assay for studying the hydroxylation of two evolutionarily conserved prolines (P402 and P564) simultaneously in the intrinsically disordered oxygen-dependent degradation domain of hypoxic-inducible factor 1α by exploiting the "proton-less" nature of prolines. We show unambiguously that P564 is rapidly hydroxylated in a time-resolved manner while P402 hydroxylation lags significantly behind that of P564. The differential hydroxylation rate was negligibly influenced by the binding affinity to prolyl-hydroxylase enzyme, but rather by the surrounding amino acid composition, particularly the conserved tyrosine residue at the +1 position to P564. These findings support the unanticipated notion that the evolutionarily conserved P402 seemingly has a minimal impact in normal oxygen-sensing pathway.


Asunto(s)
Subunidad alfa del Factor 1 Inducible por Hipoxia , Proteínas Intrínsecamente Desordenadas , Prolina , Hidroxilación , Subunidad alfa del Factor 1 Inducible por Hipoxia/metabolismo , Subunidad alfa del Factor 1 Inducible por Hipoxia/química , Prolina/metabolismo , Proteínas Intrínsecamente Desordenadas/metabolismo , Proteínas Intrínsecamente Desordenadas/química , Humanos , Procesamiento Proteico-Postraduccional , Espectroscopía de Resonancia Magnética/métodos
5.
RNA ; 2024 Aug 08.
Artículo en Inglés | MEDLINE | ID: mdl-39117455

RESUMEN

Many RNA binding proteins (RBPs) contain low-complexity domains (LCDs) with prion-like compositions. These long intrinsically disordered regions regulate their solubility, contributing to their physiological roles in RNA processing and organization. However, this also makes these RBPs prone to pathological misfolding and aggregation that are characteristic of neurodegenerative diseases. For example, TAR DNA-binding protein 43 (TDP-43) forms pathological aggregates associated with amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). While molecular chaperones are well-known suppressors of these aberrant events, we recently reported that highly disordered, hydrophilic and charged heat-resistant obscure (Hero) proteins may have similar effects. Specifically, Hero proteins can maintain the activity of other proteins from denaturing conditions in vitro, while their overexpression can suppress cellular aggregation and toxicity associated with aggregation-prone proteins. However, it is unclear how these protective effects are achieved. Here, we utilized single-molecule FRET to monitor the conformations of the aggregation-prone prion-like LCD of TDP-43. While we observed high conformational heterogeneity in wild-type LCD, the ALS-associated mutation A315T promoted collapsed conformations. In contrast, an Hsp40 chaperone, DNAJA2, and a Hero protein, Hero11 stabilized extended states of the LCD, consistent with their ability to suppress the aggregation of TDP-43. Our results link single-molecule effects on conformation to macro effects on bulk aggregation, where a Hero protein, like a chaperone, can maintain the conformational integrity of a client protein to prevent its aggregation.

6.
bioRxiv ; 2024 Aug 04.
Artículo en Inglés | MEDLINE | ID: mdl-39131319

RESUMEN

Brain functioning relies on orchestrated synaptic vesicle dynamics and controlled neurotransmitter release. Multiple biomolecular condensates coexist at the pre- and post-synapse and they are driven by condensation that combines binding, phase separation, and percolation. In pre-synapses, intrinsically disordered regions (IDRs) of synaptic proteins are drivers of condensation that enable clustering of synaptic vesicles (SVs). Although sequences of IDRs are poorly conserved across evolution, our computational analysis reveals the existence of non-random compositional biases and sequence patterns (molecular grammars) in IDRs of pre-synaptic proteins. For example, synapsin-1, which is essential for condensation of SVs, contains a conserved valence of arginine residues and blocks of polar and proline residues that are segregated from one another along the linear sequence. We show that these conserved features are crucial for driving synapsin-1 condensation in vitro and in cells. Our results highlight how conserved molecular grammars drive the condensation of key proteins at the pre-synapse.

7.
Int J Mol Sci ; 25(15)2024 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-39125972

RESUMEN

In this work, we explored the intrinsic disorder status of the three members of the synuclein family of proteins-α-, ß-, and γ-synucleins-and showed that although all three human synucleins are highly disordered, the highest levels of disorder are observed in γ-synuclein. Our analysis of the peculiarities of the amino acid sequences and modeled 3D structures of the human synuclein family members revealed that the pathological mutations A30P, E46K, H50Q, A53T, and A53E associated with the early onset of Parkinson's disease caused some increase in the local disorder propensity of human α-synuclein. A comparative sequence-based analysis of the synuclein proteins from various evolutionary distant species and evaluation of their levels of intrinsic disorder using a set of commonly used bioinformatics tools revealed that, irrespective of their origin, all members of the synuclein family analyzed in this study were predicted to be highly disordered proteins, indicating that their intrinsically disordered nature represents an evolutionary conserved and therefore functionally important feature. A detailed functional disorder analysis of the proteins in the interactomes of the human synuclein family members utilizing a set of commonly used disorder analysis tools showed that the human α-synuclein interactome has relatively higher levels of intrinsic disorder as compared with the interactomes of human ß- and γ- synucleins and revealed that, relative to the ß- and γ-synuclein interactomes, α-synuclein interactors are involved in a much broader spectrum of highly diversified functional pathways. Although proteins interacting with three human synucleins were characterized by highly diversified functionalities, this analysis also revealed that the interactors of three human synucleins were involved in three common functional pathways, such as the synaptic vesicle cycle, serotonergic synapse, and retrograde endocannabinoid signaling. Taken together, these observations highlight the critical importance of the intrinsic disorder of human synucleins and their interactors in various neuronal processes.


Asunto(s)
alfa-Sinucleína , Humanos , alfa-Sinucleína/metabolismo , alfa-Sinucleína/química , alfa-Sinucleína/genética , Proteínas Intrínsecamente Desordenadas/metabolismo , Proteínas Intrínsecamente Desordenadas/química , Proteínas Intrínsecamente Desordenadas/genética , Secuencia de Aminoácidos , Sinucleína beta/metabolismo , Sinucleína beta/genética , Sinucleína beta/química , gamma-Sinucleína/metabolismo , gamma-Sinucleína/genética , Enfermedad de Parkinson/metabolismo , Enfermedad de Parkinson/genética , Sinucleínas/metabolismo , Sinucleínas/genética , Modelos Moleculares , Mutación
8.
Proc Natl Acad Sci U S A ; 121(33): e2409167121, 2024 Aug 13.
Artículo en Inglés | MEDLINE | ID: mdl-39116133

RESUMEN

Linker histones play an essential role in chromatin packaging by facilitating compaction of the 11-nm fiber of nucleosomal "beads on a string." The result is a heterogeneous condensed state with local properties that range from dynamic, irregular, and liquid-like to stable and regular structures (the 30-nm fiber), which in turn impact chromatin-dependent activities at a fundamental level. The properties of the condensed state depend on the type of linker histone, particularly on the highly disordered C-terminal tail, which is the most variable region of the protein, both between species, and within the various subtypes and cell-type specific variants of a given organism. We have developed an in vitro model system comprising linker histone tail and linker DNA, which although very minimal, displays surprisingly complex behavior, and is sufficient to model the known states of linker histone-condensed chromatin: disordered "fuzzy" complexes ("open" chromatin), dense liquid-like assemblies (dynamic condensates), and higher-order structures (organized 30-nm fibers). A crucial advantage of such a simple model is that it allows the study of the various condensed states by NMR, circular dichroism, and scattering methods. Moreover, it allows capture of the thermodynamics underpinning the transitions between states through calorimetry. We have leveraged this to rationalize the distinct condensing properties of linker histone subtypes and variants across species that are encoded by the amino acid content of their C-terminal tails. Three properties emerge as key to defining the condensed state: charge density, lysine/arginine ratio, and proline-free regions, and we evaluate each separately using a strategic mutagenesis approach.


Asunto(s)
ADN , Histonas , Nucleosomas , Histonas/química , Histonas/metabolismo , Histonas/genética , ADN/química , ADN/metabolismo , Nucleosomas/metabolismo , Nucleosomas/química , Cromatina/química , Cromatina/metabolismo , Cromatina/genética , Animales , Humanos
9.
mBio ; : e0135824, 2024 Aug 29.
Artículo en Inglés | MEDLINE | ID: mdl-39207096

RESUMEN

Carboxysomes are proteinaceous organelles featuring icosahedral protein shells that enclose the carbon-fixing enzymes, ribulose-1,5-bisphosphate carboxylase oxygenase (Rubisco), along with carbonic anhydrase. The intrinsically disordered scaffolding protein CsoS2 plays a vital role in the construction of α-carboxysomes through bridging the shell and cargo enzymes. The N-terminal domain of CsoS2 binds Rubisco and facilitates Rubisco packaging within the α-carboxysome, whereas the C-terminal domain of CsoS2 (CsoS2-C) anchors to the shell and promotes shell assembly. However, the role of the middle region of CsoS2 (CsoS2-M) has remained elusive. Here, we conducted in-depth examinations on the function of CsoS2-M in the assembly of the α-carboxysome shell by generating a series of recombinant shell variants in the absence of cargos. Our results reveal that CsoS2-M assists CsoS2-C in the assembly of the α-carboxysome shell and plays an important role in shaping the α-carboxysome shell through enhancing the association of shell proteins on both the facet-facet interfaces and flat shell facets. Moreover, CsoS2-M is responsible for recruiting the C-terminal truncated isoform of CsoS2, CsoS2A, into α-carboxysomes, which is crucial for Rubisco encapsulation and packaging. This study not only deepens our knowledge of how the carboxysome shell is constructed and regulated but also lays the groundwork for engineering and repurposing carboxysome-based nanostructures for diverse biotechnological purposes. IMPORTANCE: Carboxysomes are a paradigm of organelle-like structures in cyanobacteria and many proteobacteria. These nanoscale compartments enclose Rubisco and carbonic anhydrase within an icosahedral virus-like shell to improve CO2 fixation, playing a vital role in the global carbon cycle. Understanding how the carboxysomes are formed is not only important for basic research studies but also holds promise for repurposing carboxysomes in bioengineering applications. In this study, we focuses on a specific scaffolding protein called CsoS2, which is involved in facilitating the assembly of α-type carboxysomes. By deciphering the functions of different parts of CsoS2, especially its middle region, we provide new insights into how CsoS2 drives the stepwise assembly of the carboxysome at the molecular level. This knowledge will guide the rational design and reprogramming of carboxysome nanostructures for many biotechnological applications.

10.
Int J Biol Macromol ; 277(Pt 3): 134291, 2024 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-39089542

RESUMEN

Tuftelin Interacting Protein 11 (TFIP11) was identified as a critical human spliceosome assembly regulator, interacting with multiple proteins and localising in membrane-less organelles. However, a lack of structural information on TFIP11 limits the rationalisation of its biological role. TFIP11 is predicted as an intrinsically disordered protein (IDP), and more specifically concerning its N-terminal (N-TER) region. IDPs lack a defined tertiary structure, existing as a dynamic conformational ensemble, favouring protein-protein and protein-RNA interactions. IDPs are involved in liquid-liquid phase separation (LLPS), driving the formation of subnuclear compartments. Combining disorder prediction, molecular dynamics, and spectroscopy methods, this contribution shows the first evidence TFIP11 N-TER is a polyampholytic IDP, exhibiting a structural duality with the coexistence of ordered and disordered assemblies, depending on the ionic strength. Increasing the salt concentration enhances the protein conformational flexibility, presenting a more globule-like shape, and a fuzzier unstructured arrangement that could favour LLPS and protein-RNA interaction. The most charged and hydrophilic regions are the most impacted, including the G-Patch domain essential to TFIP11 function. This study gives a better understanding of the salt-dependent conformational behaviour of the N-TER TFIP11, supporting the hypothesis of the formation of different types of protein assembly, in line with its multiple biological roles.


Asunto(s)
Proteínas Intrínsecamente Desordenadas , Proteínas Intrínsecamente Desordenadas/química , Proteínas Intrínsecamente Desordenadas/metabolismo , Proteínas Intrínsecamente Desordenadas/genética , Humanos , Conformación Proteica , Simulación de Dinámica Molecular , Proteínas de Unión al ARN/química , Proteínas de Unión al ARN/metabolismo , Factores de Empalme de ARN/química , Factores de Empalme de ARN/metabolismo , Factores de Empalme de ARN/genética , Sales (Química)/química , Dominios Proteicos
11.
Virus Res ; 348: 199446, 2024 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-39127239

RESUMEN

The Human papillomavirus (HPV) causes tumors in part by hijacking the host cell cycle and forcing uncontrolled cellular division. While there are >200 genotypes of HPV, 15 are classified as high-risk and have been shown to transform infected cells and contribute to tumor formation. The remaining low-risk genotypes are not considered oncogenic and result in benign skin lesions. In high-risk HPV, the oncoprotein E7 contributes to the dysregulation of cell cycle regulatory mechanisms. High-risk E7 is phosphorylated in cells at two conserved serine residues by Casein Kinase 2 (CK2) and this phosphorylation event increases binding affinity for cellular proteins such as the tumor suppressor retinoblastoma (pRb). While low-risk E7 possesses similar serine residues, it is phosphorylated to a lesser degree in cells and has decreased binding capabilities. When E7 binding affinity is decreased, it is less able to facilitate complex interactions between proteins and therefore has less capability to dysregulate the cell cycle. By comparing E7 protein sequences from both low- and high-risk HPV variants and using site-directed mutagenesis combined with NMR spectroscopy and cell-based assays, we demonstrate that the presence of two key nonpolar valine residues within the CK2 recognition sequence, present in low-risk E7, reduces serine phosphorylation efficiency relative to high-risk E7. This results in significant loss of the ability of E7 to degrade the retinoblastoma tumor suppressor protein, thus also reducing the ability of E7 to increase cellular proliferation and reduce senescence. This provides additional insight into the differential E7-mediated outcomes when cells are infected with high-risk verses low-risk HPV. Understanding these oncogenic differences may be important to developing targeted treatment options for HPV-induced cancers.


Asunto(s)
Proteínas E7 de Papillomavirus , Fosforilación , Proteínas E7 de Papillomavirus/metabolismo , Proteínas E7 de Papillomavirus/genética , Humanos , Quinasa de la Caseína II/metabolismo , Quinasa de la Caseína II/genética , Infecciones por Papillomavirus/virología , Infecciones por Papillomavirus/metabolismo , Infecciones por Papillomavirus/genética , Unión Proteica , Proteína de Retinoblastoma/metabolismo , Proteína de Retinoblastoma/genética , Papillomaviridae/genética , Papillomaviridae/metabolismo , Papillomaviridae/fisiología , Ciclo Celular , Mutagénesis Sitio-Dirigida
12.
Viruses ; 16(8)2024 Aug 19.
Artículo en Inglés | MEDLINE | ID: mdl-39205298

RESUMEN

An intrinsically disordered protein (IDP) or region (IDR) lacks or has little protein structure but still maintains function. This lack of structure creates flexibility and fluidity, allowing multiple protein conformations and potentially transient interactions with more than one partner. Caliciviruses are positive-sense ssRNA viruses, containing a relatively small genome of 7.6-8.6 kb and have a broad host range. Many viral proteins are known to contain IDRs, which benefit smaller viral genomes by expanding the functional proteome through the multifunctional nature of the IDR. The percentage of intrinsically disordered residues within the total proteome for each calicivirus type species can range between 8 and 23%, and IDRs have been experimentally identified in NS1-2, VPg and RdRP proteins. The IDRs within a protein are not well conserved across the genera, and whether this correlates to different activities or increased tolerance to mutations, driving virus adaptation to new selection pressures, is unknown. The function of norovirus NS1-2 has not yet been fully elucidated but includes involvement in host cell tropism, the promotion of viral spread and the suppression of host interferon-λ responses. These functions and the presence of host cell-like linear motifs that interact with host cell caspases and VAPA/B are all found or affected by the disordered region of norovirus NS1-2. The IDRs of calicivirus VPg are involved in viral transcription and translation, RNA binding, nucleotidylylation and cell cycle arrest, and the N-terminal IDR within the human norovirus RdRP could potentially drive liquid-liquid phase separation. This review identifies and summarises the IDRs of proteins within the Caliciviridae family and their importance during viral replication and subsequent host interactions.


Asunto(s)
Caliciviridae , Proteínas Intrínsecamente Desordenadas , Proteínas Virales , Caliciviridae/genética , Caliciviridae/química , Humanos , Proteínas Virales/genética , Proteínas Virales/metabolismo , Proteínas Virales/química , Proteínas Intrínsecamente Desordenadas/química , Proteínas Intrínsecamente Desordenadas/metabolismo , Proteínas Intrínsecamente Desordenadas/genética , Genoma Viral , Infecciones por Caliciviridae/virología , Animales , Proteoma , Replicación Viral
13.
Cell Rep ; 43(7): 114419, 2024 Jul 23.
Artículo en Inglés | MEDLINE | ID: mdl-38985672

RESUMEN

The compaction of chromatin into mitotic chromosomes is essential for faithful transmission of the genome during cell division. In eukaryotes, chromosome morphogenesis is regulated by the condensin complex, though the exact mechanism used to target condensin to chromatin and initiate condensation is not understood. Here, we reveal that condensin contains an intrinsically disordered region (IDR) that modulates its association with chromatin in early mitosis and exhibits phase separation. We describe DNA-binding motifs within the IDR that, upon deletion, inflict striking defects in chromosome condensation and segregation, ill-timed condensin turnover on chromatin, and cell death. Importantly, we demonstrate that the condensin IDR can impart cell cycle regulatory functions when transferred to other subunits within the complex, indicating its autonomous nature. Collectively, our study unveils the molecular basis for the initiation of chromosome condensation in early mitosis and how this process ultimately promotes genomic stability and faultless cell division.


Asunto(s)
Adenosina Trifosfatasas , Proteínas de Unión al ADN , Mitosis , Complejos Multiproteicos , Proteínas de Unión al ADN/metabolismo , Proteínas de Unión al ADN/genética , Complejos Multiproteicos/metabolismo , Adenosina Trifosfatasas/metabolismo , Cromatina/metabolismo , ADN/metabolismo , Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/genética , Cromosomas/metabolismo , Unión Proteica , Segregación Cromosómica , Proteínas de Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética
14.
bioRxiv ; 2024 Jul 16.
Artículo en Inglés | MEDLINE | ID: mdl-39071267

RESUMEN

Proteins which bind intrinsically disordered proteins (IDPs) and intrinsically disordered regions (IDRs) with high affinity and specificity could have considerable utility for therapeutic and diagnostic applications. However, a general methodology for targeting IDPs/IDRs has yet to be developed. Here, we show that starting only from the target sequence of the input, and freely sampling both target and binding protein conformation, RFdiffusion can generate binders to IDPs and IDRs in a wide range of conformations. We use this approach to generate binders to the IDPs Amylin, C-peptide and VP48 in a range of conformations with Kds in the 3 -100nM range. The Amylin binder inhibits amyloid fibril formation and dissociates existing fibers, and enables enrichment of amylin for mass spectrometry-based detection. For the IDRs G3bp1, common gamma chain (IL2RG) and prion, we diffused binders to beta strand conformations of the targets, obtaining 10 to 100 nM affinity. The IL2RG binder colocalizes with the receptor in cells, enabling new approaches to modulating IL2 signaling. Our approach should be widely useful for creating binders to flexible IDPs/IDRs spanning a wide range of intrinsic conformational preferences.

15.
Cell Rep ; 43(8): 114525, 2024 Aug 27.
Artículo en Inglés | MEDLINE | ID: mdl-39037895

RESUMEN

Alternative polyadenylation (APA) is a critical post-transcriptional process that generates mRNA isoforms with distinct 3' untranslated regions (3' UTRs), thereby regulating mRNA localization, stability, and translational efficiency. Cell-type-specific APA extensively shapes the diversity of the cellular transcriptome, particularly during cell fate transition. Despite its recognized significance, the precise regulatory mechanisms governing cell-type-specific APA remain unclear. In this study, we uncover PQBP1 as an emerging APA regulator that actively maintains cell-specific APA profiles in neural progenitor cells (NPCs) and delicately manages the equilibrium between NPC proliferation and differentiation. Multi-omics analysis shows that PQBP1 directly interacts with the upstream UGUA elements, impeding the recruitment of the CFIm complex and influencing polyadenylation site selection within genes associated with the cell cycle. Our findings elucidate the molecular mechanism by which PQBP1 orchestrates dynamic APA changes during neurogenesis, providing valuable insights into the precise regulation of cell-type-specific APA and the underlying pathogenic mechanisms in neurodevelopmental disorders.


Asunto(s)
Células-Madre Neurales , Neurogénesis , Poliadenilación , Células-Madre Neurales/metabolismo , Células-Madre Neurales/citología , Animales , Humanos , Ratones , Diferenciación Celular , Regiones no Traducidas 3'/genética , Proteínas de Unión al ADN/metabolismo , Proteínas de Unión al ADN/genética , Proliferación Celular , ARN Mensajero/metabolismo , ARN Mensajero/genética , Proteínas Nucleares/metabolismo , Proteínas Nucleares/genética
16.
J Biol Chem ; 300(9): 107607, 2024 Jul 30.
Artículo en Inglés | MEDLINE | ID: mdl-39084460

RESUMEN

The N-terminal region of the human lysine-specific demethylase 1 (LSD1) has no predicted structural elements, contains a nuclear localization signal (NLS), undergoes multiple posttranslational modifications (PTMs), and acts as a protein-protein interaction hub. This intrinsically disordered region (IDR) extends from core LSD1 structure, resides atop the catalytic active site, and is known to be dispensable for catalysis. Here, we show differential nucleosome binding between the full-length and an N terminus deleted LSD1 and identify that a conserved NLS and PTM containing element of the N terminus contains an alpha helical structure, and that this conserved element impacts demethylation. Enzyme assays reveal that LSD1's own electropositive NLS amino acids 107 to 120 inhibit demethylation activity on a model histone 3 lysine 4 dimethyl (H3K4me2) peptide (Kiapp âˆ¼ 3.3 µM) and histone 3 lysine 4 dimethyl nucleosome substrates (IC50 ∼ 30.4 µM), likely mimicking the histone H3 tail. Further, when the identical, inhibitory NLS region contains phosphomimetic modifications, inhibition is partially relieved. Based upon these results and biophysical data, a regulatory mechanism for the LSD1-catalyzed demethylation reaction is proposed whereby NLS-mediated autoinhibition can occur through electrostatic interactions, and be partially relieved through phosphorylation that occurs proximal to the NLS. Taken together, the results highlight a dynamic and synergistic role for PTMs, intrinsically disordered regions, and structured regions near LSD1 active site and introduces the notion that phosphorylated mediated NLS regions can function to fine-tune chromatin modifying enzyme activity.

17.
Proc Natl Acad Sci U S A ; 121(29): e2407744121, 2024 Jul 16.
Artículo en Inglés | MEDLINE | ID: mdl-38985766

RESUMEN

G protein-coupled receptors (GPCRs) control intracellular signaling cascades via agonist-dependent coupling to intracellular transducers including heterotrimeric G proteins, GPCR kinases (GRKs), and arrestins. In addition to their critical interactions with the transmembrane core of active GPCRs, all three classes of transducers have also been reported to interact with receptor C-terminal domains (CTDs). An underexplored aspect of GPCR CTDs is their possible role as lipid sensors given their proximity to the membrane. CTD-membrane interactions have the potential to control the accessibility of key regulatory CTD residues to downstream effectors and transducers. Here, we report that the CTDs of two closely related family C GPCRs, metabotropic glutamate receptor 2 (mGluR2) and mGluR3, bind to membranes and that this interaction can regulate receptor function. We first characterize CTD structure with NMR spectroscopy, revealing lipid composition-dependent modes of membrane binding. Using molecular dynamics simulations and structure-guided mutagenesis, we then identify key conserved residues and cancer-associated mutations that modulate CTD-membrane binding. Finally, we provide evidence that mGluR3 transducer coupling is controlled by CTD-membrane interactions in live cells, which may be subject to regulation by CTD phosphorylation and changes in membrane composition. This work reveals an additional mechanism of GPCR modulation, suggesting that CTD-membrane binding may be a general regulatory mode throughout the broad GPCR superfamily.


Asunto(s)
Membrana Celular , Simulación de Dinámica Molecular , Receptores de Glutamato Metabotrópico , Humanos , Receptores de Glutamato Metabotrópico/metabolismo , Receptores de Glutamato Metabotrópico/química , Receptores de Glutamato Metabotrópico/genética , Membrana Celular/metabolismo , Dominios Proteicos , Receptores Acoplados a Proteínas G/metabolismo , Receptores Acoplados a Proteínas G/química , Unión Proteica , Células HEK293 , Proteínas Intrínsecamente Desordenadas/metabolismo , Proteínas Intrínsecamente Desordenadas/química , Proteínas Intrínsecamente Desordenadas/genética , Transducción de Señal
18.
Biotechnol Bioeng ; 2024 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-38951956

RESUMEN

In recent decades, biocatalysis has emerged as an important alternative to chemical catalysis in pharmaceutical manufacturing. Biocatalysis is attractive because enzymatic cascades can synthesize complex molecules with incredible selectivity, yield, and in an environmentally benign manner. Enzymes for pharmaceutical biocatalysis are typically used in their unpurified state, since it is time-consuming and cost-prohibitive to purify enzymes using conventional chromatographic processes at scale. However, impurities present in crude enzyme preparations can consume substrate, generate unwanted byproducts, as well as make the isolation of desired products more cumbersome. Hence, a facile, nonchromatographic purification method would greatly benefit pharmaceutical biocatalysis. To address this issue, here we have captured enzymes into membraneless compartments by fusing enzymes with an intrinsically disordered protein region, the RGG domain from LAF-1. The RGG domain can undergo liquid-liquid phase separation, forming liquid condensates triggered by changes in temperature or salt concentration. By centrifuging these liquid condensates, we have successfully purified enzyme-RGG fusions, resulting in significantly enhanced purity compared to cell lysate. Furthermore, we performed enzymatic reactions utilizing purified fusion proteins to assay enzyme activity. Results from the enzyme assays indicate that enzyme-RGG fusions purified by the centrifugation method retain enzymatic activity, with greatly reduced background activity compared to crude enzyme preparations. Our work focused on three different enzymes-a kinase, a phosphorylase, and an ATP-dependent ligase. The kinase and phosphorylase are components of the biocatalytic cascade for manufacturing molnupiravir, and we demonstrated facile co-purification of these two enzymes by co-phase separation. To conclude, enzyme capture by RGG tagging promises to overcome difficulties in bioseparations and biocatalysis for pharmaceutical synthesis.

19.
J Biol Chem ; 300(8): 107532, 2024 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-38971311

RESUMEN

All cyanobacteria and some chemoautotrophic bacteria fix CO2 into sugars using specialized proteinaceous compartments called carboxysomes. Carboxysomes enclose the enzymes Rubisco and carbonic anhydrase inside a layer of shell proteins to increase the CO2 concentration for efficient carbon fixation by Rubisco. In the ⍺-carboxysome lineage, a disordered and highly repetitive protein named CsoS2 is essential for carboxysome formation and function. Without it, the bacteria require high CO2 to grow. How does a protein predicted to be lacking structure serve as the architectural scaffold for such a vital cellular compartment? In this study, we identify key residues present in the repeats of CsoS2, VTG and Y, which are necessary for building functional ⍺-carboxysomes in vivo. These highly conserved and repetitive residues contribute to the multivalent binding interaction and phase separation behavior between CsoS2 and shell proteins. We also demonstrate 3-component reconstitution of CsoS2, Rubisco, and shell proteins into spherical condensates and show the utility of reconstitution as a biochemical tool to study carboxysome biogenesis. The precise self-assembly of thousands of proteins is crucial for carboxysome formation, and understanding this process could enable their use in alternative biological hosts or industrial processes as effective tools to fix carbon.


Asunto(s)
Proteínas Bacterianas , Proteínas Intrínsecamente Desordenadas , Ribulosa-Bifosfato Carboxilasa , Proteínas Intrínsecamente Desordenadas/metabolismo , Proteínas Intrínsecamente Desordenadas/química , Proteínas Intrínsecamente Desordenadas/genética , Ribulosa-Bifosfato Carboxilasa/metabolismo , Ribulosa-Bifosfato Carboxilasa/química , Ribulosa-Bifosfato Carboxilasa/genética , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/química , Proteínas Bacterianas/genética , Anhidrasas Carbónicas/metabolismo , Anhidrasas Carbónicas/química , Anhidrasas Carbónicas/genética , Dióxido de Carbono/metabolismo , Dióxido de Carbono/química , Secuencias de Aminoácidos , Ciclo del Carbono , Orgánulos/metabolismo
20.
Chem Asian J ; : e202400389, 2024 Jun 12.
Artículo en Inglés | MEDLINE | ID: mdl-38865098

RESUMEN

Intrinsically disordered protein regions (IDPRs) are pivotal in regulation of transcription and facilitation of signal transduction. Because of their multiple conformational states of structure, characterizing the highly flexible structures of IDPRs becomes challenging. Herein, we employed the wild-type (WT) aerolysin nanopore as a real-time biosensor for identification and monitoring of long peptides containing IDPRs. This sensor successfully identified three intrinsically disordered peptides, with the lengths up to 43 amino acids, by distinguishing the unique signatures of blockade current and duration time. The analysis of the binding constant revealed that interactions between the nanopore and peptides are critical for peptide translocation, which suggests that mechanisms beyond mere volume exclusion. Furthermore, we were able to compare the conformational stabilities of various IDPRs by examining the detailed current traces of blockade events. Our approach can detect the conformational changes of IDPR in a confined nanopore space. These insights broaden the understanding of peptide structural changes. The nanopore biosensor showed the potential to study the conformations change of IDPRs, IDPRs transmembrane interactions, and protein drug discovery.

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