RESUMEN

Anti-synthetase syndrome (AS) is a subset of idiopathic inflammatory myopathy (IIM) characterized by the presence of anti-aminoacyl-transfer RNA synthetase accompanied by myositis, interstitial lung disease and other clinical features. According to a recent multicentric study, 31% of AS patients present skin lesions compatible with dermatomyositis, but sclerodermiform features are rare. Therefore, we aimed to report the case of a patient with simultaneous diagnosis of AS, deep morphea, vasculitic neuropathy, and myelodysplastic syndrome and review the current literature regarding these uncommon associations. A 57 year old man with axial and symmetrical proximal muscle weakness, skin thickening and B symptoms, later diagnosed with PL7 + AS, deep morphea, myelodysplastic syndrome (MDS) and vasculitic neuropathy documented by histopathologic studies and immunologic assessments. Since both AS and deep morphea share the vasculopathic changes and type II interferon-induced inflammation, we hypothesize that they may share pathogenic mechanisms. The muscle biopsy of the patient was consistent with AS and showed focal neutrophil infiltration. The patient received intensive immunosuppressive therapy for AS and vasculitic neuropathy, with high dose steroids, intravenous immunoglobulin (IVIg) and rituximab. Nonetheless, he suffered an unfavorable evolution with a fatal outcome due to septic shock. Albeit sclerodermiform features are rare in patients with AS, we propose a pathogenic link among AS, deep morphea and the autoimmune/autoinflammatory signs of MDS. The vasculopathic changes along with the activation of the innate and adaptive immune system leading to the production of proinflammatory cytokines may have been one of the contributing factors for the coexisting diagnosis of the patient.

Asunto(s)

Síndromes Mielodisplásicos , Miositis , Esclerodermia Localizada , Humanos , Masculino , Persona de Mediana Edad , Miositis/inmunología , Miositis/tratamiento farmacológico , Miositis/diagnóstico , Esclerodermia Localizada/tratamiento farmacológico , Esclerodermia Localizada/inmunología , Esclerodermia Localizada/patología , Síndromes Mielodisplásicos/complicaciones , Síndromes Mielodisplásicos/inmunología , Síndromes Mielodisplásicos/tratamiento farmacológico , Síndromes Mielodisplásicos/diagnóstico , Resultado Fatal , Inmunosupresores/uso terapéutico , Autoanticuerpos/sangre , Aminoacil-ARNt Sintetasas/inmunología

RESUMEN

In this work, we formulate the following question: How the distribution of aminoacyl-tRNA synthetases (aaRSs) went from an ancestral bidirectional gene (mirror symmetry) to the symmetrical distribution of aaRSs in a six-dimensional hypercube of the Standard Genetic Code (SGC)? We assume a primeval RNY code, two Extended Genetic RNA codes type 1 and 2, and the SGC. We outline the types of symmetries of the distribution of aaRSs in each code. The symmetry groups of aaRSs in each code are described, until the symmetries of the SGC display a mirror symmetry. Considering both Extended RNA codes the 20 aaRSs were already present before the Last Universal Ancestor. These findings reveal intricacies in the diversification of aaRSs accompanied by the evolution of the genetic code.

Asunto(s)

Aminoacil-ARNt Sintetasas , Evolución Molecular , Código Genético , Aminoacil-ARNt Sintetasas/genética , ARN de Transferencia/genética , ARN

RESUMEN

Introducción: Las Enfermedades Pulmonares Intersticiales (EPI) afectan principalmente al intersticio pulmonar, con importante morbimortalidad asociada. Tienen un espectro de posibles etiologías que es cada vez más amplio. Hay una importante causalidad a partir de Enfermedades del Tejido Conectivo (ETC), describiéndose cada vez más casos asociados a Síndrome Antisintetasa, y con diversos patrones radiológicos según serología obtenida, agrupada en "Panel de Miositis" (PaM). El presente estudio de cohorte retrospectiva reúne PaMs realizados en el Hospital Santiago Oriente, correlacionando resultados con manifestaciones clínicas e imagenológicas. Material y Métodos: Se recuperaron 33 PaMs realizados entre 2017 y 2022, y a través de revisión de fichas de los pacientes de quienes provenían las PaMs se consignaron las principales manifestaciones clínicas, imagenológicas y de la serología reumatológica complementaria, estableciendo correlaciones entre múltiples variables. Resultados: Hubo 15 pacientes PaM positivos (45,4%), 8 de ellos (53%) ya contaban con alguna miopatía inflamatoria diagnosticada. Los principales hallazgos clínicos consignados fueron pápulas de Gottron, artritis, eritema heliotropo, Fenómeno de Raynaud y fiebre. El anticuerpo positivo más frecuente fue Ro-52. Se pudo objetivar ANA positivo en 10 casos (66,7%). Se identificó EPI en 66,7% de aquellos con PaM positivo, siendo la Neumonía Intersticial no específica fibrótica con Neumonía en Organización la manifestación más frecuente. No hubo asociación significativa entre manifestaciones imagenológicas y anticuerpos específicos. Se encontró ANA 1/80 en 66,7% de los casos, lo cual no se asoció a mayor riesgo de EPI. Conclusiones: Existe asociación entre varias ETC y las EPI. Destaca la importancia de los hallazgos clínicos para establecer un adecuado índice de sospecha, para dirigir oportunamente el estudio complementario (ej: PaM), y la eventual terapia específica.

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Introduction: Interstitial Lung Diseases (ILD) mainly affect the pulmonary interstitium, with significant associated morbidity and mortality. They have a spectrum of possible etiologies that is increasingly broad. There is an important causality from Connective Tissue Diseases (CTD), describing more and more cases associated with Antisynthetase Syndrome, and with different radiological patterns according to the serology obtained, enclosed into "Panel of Myositis" (PaM). This retrospective cohort study gathers PaMs performed at Hospital Santiago Oriente, PaM results are correlated with clinical and imaging manifestations. Material and Methods: 33 PaMs performed between 2017 and 2022 were saved up and by reviewing the clinical records of the patients from whom the PaMs came, their clinical and radiological manifestations and the results of their complementary rheumatological serology were recorded to establish correlations between multiple variables. Results: There were 15 positive PaMs (45.4%), 8 (53%) of them already had some diagnosed inflammatory myopathy. The main clinical findings reported were Gottron's papules, arthritis, heliotrope erythema, Raynaud's phenomenon, and fever. The most frequent positive antibody detected was Ro-52. Positive ANA could be found in 10 cases (66.7%). PID was identified in 66.7% of those with a positive PaM, being non-specific fibrotic Interstitial Pneumonia with Organizing Pneumonia being the most frequent manifestation. There was no significant association between imaging manifestations and specific antibodies. ANA 1/80 was found in 6.7% of the cases, which was not associated with an increased risk of PID. Conclusions: There is association between several CTEs and EPIs. It is necessary to highlight the importance of the clinical findings to establish an adequate index of suspicion, in order to timely direct the complementary study (eg: PaM), and the eventual specific therapy.

Asunto(s)

Humanos , Masculino , Femenino , Persona de Mediana Edad , Anciano , Enfermedades Pulmonares Intersticiales/diagnóstico , Miositis/diagnóstico , Autoanticuerpos , Estudios Retrospectivos , Enfermedades Pulmonares Intersticiales/inmunología , Enfermedades Pulmonares Intersticiales/diagnóstico por imagen , Enfermedades del Tejido Conjuntivo , Aminoacil-ARNt Sintetasas , Miositis/inmunología , Miositis/diagnóstico por imagen

RESUMEN

BACKGROUND: Anti-synthetase syndrome is a rare autoimmune disorder characterized by autoantibodies against aminoacyl-tRNA-synthetases. Inflammatory myopathy and interstitial lung disease could be present among other manifestations. Anti-Jo-1 is the most common antisynthetase antibody and is the most likely to present with the classic triad (interstitial lung disease, myositis, and arthritis), and includes more muscle and joint involvement than patients with other antisynthetase antibodies. CASE REPORT: Here, we present a case of a 60-year-old female patient with a previous diagnosis of myositis, secondary to the anti-synthetase syndrome, a complication of pyogenic myositis. CONCLUSION: The diagnosis of anti-synthetase syndrome is made by a multidisciplinary approach, and occasionally, muscle and/or lung biopsy is needed. Imaging studies, especially magnetic resonance imaging, based on findings such as muscle and fascial edema, and fatty tissue replacement, allow an optimal approach.

Asunto(s)

Aminoacil-ARNt Sintetasas , Enfermedades Pulmonares Intersticiales , Miositis , Autoanticuerpos , Femenino , Humanos , Ligasas , Enfermedades Pulmonares Intersticiales/diagnóstico , Persona de Mediana Edad , Miositis/complicaciones , Miositis/diagnóstico por imagen

RESUMEN

The evolutionary history of Class I aminoacyl-tRNA synthetases (aaRS) through the reconstruction of ancestral sequences is presented. From structural molecular modeling, we sought to understand its relationship with the acceptor arms and the tRNA anticodon loop, how this relationship was established, and the possible implications in determining the genetic code and the translation system. The results of the molecular docking showed that in 7 out 9 aaRS, the acceptor arm and the anticodon loop bond practically in the same region. Domain accretion process in aaRS and repositioning of interactions between tRNAs and aaRS are illustrated. Based on these results, we propose that the operational code and the anticodon code coexisted, competing for the aaRS catalytic region, while consequently contributed to the stabilization of these proteins.

Asunto(s)

Aminoacil-ARNt Sintetasas , Código Genético , Aminoacil-ARNt Sintetasas/genética , Anticodón/genética , Simulación del Acoplamiento Molecular , ARN de Transferencia/genética

RESUMEN

Inflammatory myofibroblastic tumor (IMT) is a lesion of intermediate biological potential with local recurrences and rare metastases found in multiple anatomical locations. We present a case of a pure intraarticular IMT of the knee, a location that has not been previously documented, with genetic confirmation of ALK-CARS fusion detected with next-generation sequencing. A 20-year-old healthy male was admitted to the orthopedic oncology department due to several months of pain and restriction in movement of his left knee. On magnetic resonance imaging, multiple intraarticular nodular lesions were seen. The patient underwent 2 synovectomies within the course of 1 year. The initial biopsy was interpreted as nodular fasciitis. The second biopsy revealed exuberant tissue displaying compact fascicles of spindle cells intermixed with myxoid areas in a background of inflammatory cells, highly suggestive for IMT. Due to the unusual intraarticular location, equivocal ALK immunostaining and the differential diagnosis with nodular fasciitis, we performed targeted next-generation sequencing using Archer FusionPlex Sarcoma panel, which can identify multiple fusions in a single assay. An ALK-CARS fusion was found, supporting the diagnosis of IMT. This report emphasizes the added value of broad molecular analysis in cases with unusual clinical presentation, equivocal immunohistochemistry, and a wide differential diagnosis.

Asunto(s)

Articulación de la Rodilla/patología , Proteínas de Fusión Oncogénica/genética , Neoplasias de los Tejidos Blandos/diagnóstico , Membrana Sinovial/patología , Aminoacil-ARNt Sintetasas/genética , Quinasa de Linfoma Anaplásico/genética , Biopsia , Procedimientos Quirúrgicos de Citorreducción , Diagnóstico Diferencial , Fascitis/diagnóstico , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Articulación de la Rodilla/diagnóstico por imagen , Articulación de la Rodilla/inmunología , Articulación de la Rodilla/cirugía , Imagen por Resonancia Magnética , Masculino , Neoplasias de los Tejidos Blandos/genética , Neoplasias de los Tejidos Blandos/inmunología , Neoplasias de los Tejidos Blandos/cirugía , Sinovectomía , Membrana Sinovial/diagnóstico por imagen , Membrana Sinovial/inmunología , Adulto Joven

RESUMEN

The KARS gene encodes the aminoacyl-tRNA synthetase (aaRS), which activates and joins the lysin with its corresponding transfer RNA (tRNA) through the ATP-dependent aminoacylation of the amino acid. KARS gene mutations have been linked to diverse neurologic phenotypes, such as neurosensorial hearing loss, leukodystrophy, microcephaly, developmental delay or regression, peripheral neuropathy, cardiomyopathy, the impairment of the mitochondrial respiratory chain, and hyperlactatemia, among others. This article presents the case of a Colombian pediatric patient with two pathological missense variants in a compound heterozygous state in the KARS gene and, in addition to the case report, the paper reviews the literature for other cases of KARS1-associated leukodystrophy.

Asunto(s)

Aminoacil-ARNt Sintetasas/genética , Mutación/genética , Niño , Pérdida Auditiva/genética , Humanos , América Latina , Masculino , Mitocondrias/genética

RESUMEN

We determined the identity elements of each tRNA isoacceptor for the three domains of life: Eubacteria, Archaea, and Eukarya. Our analyses encompass the most updated and curated available databases using an information theory approach. We obtained a collection of identity clusters for each of the isoacceptors of the 20 canonical amino acids for the three major domains of life. The identity clusters for all isoacceptors are compared within and among the three domains to determine their pattern of differentiation and to shed light on the evolution of the identity elements.

Asunto(s)

Archaea/genética , Bacterias/genética , Evolución Biológica , Eucariontes/genética , Conformación de Ácido Nucleico , ARN de Transferencia/química , Aminoácidos/química , Aminoacil-ARNt Sintetasas/genética , Anticodón/genética , Análisis por Conglomerados , Evolución Molecular , Teoría de la Información , Filogenia

RESUMEN

The Salmonella enterica serovar Typhimurium sequence type 213 (ST213) emerged as a predominant genotype in Mexico. It is characterized by harboring multidrug resistance (MDR) IncC plasmids (previously IncA/C) and the lack of the Salmonella virulence plasmid (pSTV). Here we show that the D6-like plasmid prophage is present in most of the ST213 strains. We used the reported nucleotide sequence of YU39 plasmid (pYU39_89) to design a PCR typing scheme for the D6-like plasmid prophages, and determined the complete nucleotide sequences for the D6-like prophages of three additional ST213 strains (YU07-18, SL26 and SO21). Two prophage variants were described: i) a complete prophage, containing homologous sequences for most of the genetic modules described in P1 and D6 phages, which most likely allow for the lytic and lysogenic lifestyles; and ii) an incomplete prophage, lacking a 15 kb region containing morphogenesis genes, suggesting that it is defective. The tail fiber gene inversion region was the most divergent one between D6 and pYU39_89 genomes, suggesting the production of a distinct set of tail fibers, which could be involved in host range preferences. A glutaminyl-tRNA synthetase gene (glnS), which could be involved in providing host cell increased fitness or plasmid maintenance functions, was found in all D6-like genomes. Population level analysis revealed a biogeographic pattern of distribution of these plasmid-phages and specific associations with variants of MDR IncC plasmids. Statistically significant associations were found between the two prophage variants (p75 or p89), the type of IncC plasmids (I or II) and geographic isolation regions (Sonora, San Luis Potosí, Michoacán and Yucatán). This work integrates results from molecular typing, genomics and epidemiology to provide a broad overview for the evolution of an emergent Salmonella genotype.

Asunto(s)

Plásmidos/metabolismo , Profagos/fisiología , Salmonella typhimurium/patogenicidad , Aminoacil-ARNt Sintetasas/genética , Evolución Molecular , Genoma Viral , Genómica/métodos , Genotipo , Plásmidos/genética , Reacción en Cadena de la Polimerasa , Profagos/genética , Profagos/aislamiento & purificación , Salmonella typhimurium/genética , Salmonella typhimurium/virología , Proteínas Virales/genética , Virulencia/genética

RESUMEN

Theories of the origin of the genetic code typically appeal to natural selection and/or mutation of hereditable traits to explain its regularities and error robustness, yet the present translation system presupposes high-fidelity replication. Woese's solution to this bootstrapping problem was to assume that code optimization had played a key role in reducing the effect of errors caused by the early translation system. He further conjectured that initially evolution was dominated by horizontal exchange of cellular components among loosely organized protocells ("progenotes"), rather than by vertical transmission of genes. Here we simulated such communal evolution based on horizontal transfer of code fragments, possibly involving pairs of tRNAs and their cognate aminoacyl tRNA synthetases or a precursor tRNA ribozyme capable of catalysing its own aminoacylation, by using an iterated learning model. This is the first model to confirm Woese's conjecture that regularity, optimality, and (near) universality could have emerged via horizontal interactions alone.

Asunto(s)

Evolución Molecular , Transferencia de Gen Horizontal , Código Genético , Modelos Genéticos , Biosíntesis de Proteínas , Aminoacil-ARNt Sintetasas/genética , Aminoacil-ARNt Sintetasas/metabolismo , Aminoacilación , Codón , Simulación por Computador , Extinción Biológica , Origen de la Vida , ARN Catalítico/genética , ARN Catalítico/metabolismo , ARN de Transferencia/genética , ARN de Transferencia/metabolismo

RESUMEN

The decipherment of the tRNA's operational code, known as the identity problem, requires the location of the sites in the tRNA structure that are involved in their correct recognition by the corresponding aminoacyl-tRNA synthetase. In this work, we determine the identity elements of each tRNA isoacceptor by means of the variation of information measure from information theory. We show that all isoacceptors exhibit sites associated with some bases of the anticodon. These sites form clusters that are scattered along the tRNA structure. The clusters determine the identity elements of each tRNA. We derive a catalogue of clustered sites for each tRNA that expands previously reported elements.

Asunto(s)

Aminoacil-ARNt Sintetasas/química , Anticodón/química , ARN de Transferencia/química , Evolución Molecular

RESUMEN

BACKGROUND: The amino acid response (AAR) is an evolutionarily conserved protective mechanism activated by amino acid deficiency through a key kinase, general control nonderepressible 2. In addition to mobilizing amino acids, the AAR broadly affects gene and protein expression in a variety of pathways and elicits antifibrotic, autophagic, and anti-inflammatory activities. However, little is known regarding its role in cardiac stress. Our aim was to investigate the effects of halofuginone, a prolyl-tRNA synthetase inhibitor, on the AAR pathway in cardiac fibroblasts, cardiomyocytes, and in mouse models of cardiac stress and failure. METHODS AND RESULTS: Consistent with its ability to inhibit prolyl-tRNA synthetase, halofuginone elicited a general control nonderepressible 2-dependent activation of the AAR pathway in cardiac fibroblasts as evidenced by activation of known AAR target genes, broad regulation of the transcriptome and proteome, and reversal by l-proline supplementation. Halofuginone was examined in 3 mouse models of cardiac stress: angiotensin II/phenylephrine, transverse aortic constriction, and acute ischemia reperfusion injury. It activated the AAR pathway in the heart, improved survival, pulmonary congestion, left ventricle remodeling/fibrosis, and left ventricular function, and rescued ischemic myocardium. In human cardiac fibroblasts, halofuginone profoundly reduced collagen deposition in a general control nonderepressible 2-dependent manner and suppressed the extracellular matrix proteome. In human induced pluripotent stem cell-derived cardiomyocytes, halofuginone blocked gene expression associated with endothelin-1-mediated activation of pathologic hypertrophy and restored autophagy in a general control nonderepressible 2/eIF2α-dependent manner. CONCLUSIONS: Halofuginone activated the AAR pathway in the heart and attenuated the structural and functional effects of cardiac stress.

Asunto(s)

Aminoácidos/metabolismo , Inhibidores Enzimáticos/farmacología , Fibroblastos/efectos de los fármacos , Insuficiencia Cardíaca/prevención & control , Miocitos Cardíacos/efectos de los fármacos , Piperidinas/farmacología , Inhibidores de la Síntesis de la Proteína/farmacología , Quinazolinonas/farmacología , Estrés Fisiológico , Aminoácidos/deficiencia , Aminoacil-ARNt Sintetasas/antagonistas & inhibidores , Aminoacil-ARNt Sintetasas/metabolismo , Animales , Autofagia/efectos de los fármacos , Células Cultivadas , Modelos Animales de Enfermedad , Relación Dosis-Respuesta a Droga , Fibroblastos/metabolismo , Fibroblastos/patología , Fibrosis , Insuficiencia Cardíaca/metabolismo , Insuficiencia Cardíaca/patología , Insuficiencia Cardíaca/fisiopatología , Humanos , Hipertrofia Ventricular Izquierda/metabolismo , Hipertrofia Ventricular Izquierda/patología , Hipertrofia Ventricular Izquierda/fisiopatología , Hipertrofia Ventricular Izquierda/prevención & control , Células Madre Pluripotentes Inducidas/efectos de los fármacos , Células Madre Pluripotentes Inducidas/metabolismo , Masculino , Ratones Endogámicos C57BL , Miocitos Cardíacos/metabolismo , Miocitos Cardíacos/patología , Proteínas Serina-Treonina Quinasas/metabolismo , Factores de Tiempo , Función Ventricular Izquierda/efectos de los fármacos , Remodelación Ventricular/efectos de los fármacos

RESUMEN

Transfer RNAs (tRNAs) are the macromolecules that transfer activated amino acids from aminoacyl-tRNA synthetases to the ribosome, where they are used for the mRNA guided synthesis of proteins. Transfer RNAs are ancient molecules, perhaps even predating the existence of the translation machinery. Albeit old, these molecules are tremendously conserved, a characteristic that is well illustrated by the fact that some bacterial tRNAs are efficient and specific substrates of eukaryotic aminoacyl-tRNA synthetases and ribosomes. Considering their ancient origin and high structural conservation, it is not surprising that tRNAs have been hijacked during evolution for functions outside of translation. These roles beyond translation include synthetic, regulatory and information functions within the cell. Here we provide an overview of the non-canonical roles of tRNAs and their mimics in bacteria, and discuss some of the common themes that arise when comparing these different functions.

Asunto(s)

Bacterias/genética , ARN de Transferencia/fisiología , Aminoacil-ARNt Sintetasas/genética , ARN Bacteriano/química , ARN Bacteriano/fisiología , ARN de Transferencia/química

RESUMEN

Diabetic nephropathy is the leading cause of end-stage kidney disease in the world. Many single nucleotide polymorphisms (SNPs) have been associated with diabetic nephropathy. SNPs at the 4.1 protein ezrin, radixin, moesin domain 3 (FRMD3) and cysteinyl t-RNA synthetase (CARS) genes have a well-established relationship with diabetic nephropathy. However, this association has not been evaluated in a Kuwaiti population. DNA was extracted from blood samples obtained from patients with diabetic nephropathy (N = 38); the genes of interest were amplified, and the SNPs were genotypes. Diabetics without nephropathy (N = 64) were used as controls. The risk (G and C) and non-risk (C and T) allele frequencies of the SNPs at the rs1888747 and rs739401 loci of FRMD3 and CARS, respectively, did not differ significantly between the diabetics with (case) and without (control) nephropathy (P > 0.05). These findings suggest that the molecular mechanisms involved in diabetic nephropathy may be different in a Kuwaiti population, compared to other populations (such as Japanese and Caucasian Europeans). The discrepancies observed in our study could also be attributed to the smaller sample size analyzed in this study. Therefore, further analyses with larger samples are required to identify the susceptibility genes in a Middle-Eastern population.

Asunto(s)

Aminoacil-ARNt Sintetasas/genética , Diabetes Mellitus Tipo 1/genética , Diabetes Mellitus Tipo 2/genética , Nefropatías Diabéticas/genética , Polimorfismo de Nucleótido Simple , Insuficiencia Renal Crónica/genética , Proteínas Supresoras de Tumor/genética , Alelos , Proteínas del Citoesqueleto/genética , Diabetes Mellitus Tipo 1/patología , Diabetes Mellitus Tipo 2/patología , Nefropatías Diabéticas/patología , Expresión Génica , Frecuencia de los Genes , Estudios de Asociación Genética , Predisposición Genética a la Enfermedad , Haplotipos , Humanos , Kuwait , Proteínas de la Membrana/genética , Insuficiencia Renal Crónica/patología

RESUMEN

Recently, a large body of evidences indicates the existence in the mitochondrial matrix of foci that contain different proteins involved in mitochondrial RNA metabolism. Some of these proteins have a pentatricopeptide repeat motif that constitutes their RNA-binding structures. Here we report that MSC6, a mitochondrial pentatricopeptide protein of unknown function, is a multi copy suppressor of mutations in QRS1/HER2 a component of the trimeric complex that catalyzes the transamidation of glutamyl-tRNAQ to glutaminyl-tRNAQ. This is an essential step in mitochondrial translation because of the lack of a specific mitochondrial aminoacyl glutaminyl-tRNA synthetase. MSC6 over-expression did not abolish translation of an aberrant variant form of Cox2p detected in QRS1/HER2 mutants, arguing against a suppression mechanism that bypasses Qrs1p function. A slight decrement of the mitochondrial translation capacity as well as diminished growth on respiratory carbon sources media for respiratory activity was observed in the msc6 null mutant. Additionally, the msc6 null mutant did not display any impairment in RNA transcription, processing or turnover. We concluded that Msc6p is a mitochondrial matrix protein and further studies are required to indicate the specific function of Msc6p in mitochondrial translation.

Asunto(s)

Aminoacil-ARNt Sintetasas/genética , Aminoacil-ARNt Sintetasas/metabolismo , Proteínas del Complejo de Cadena de Transporte de Electrón , Expresión Génica , Mitocondrias/genética , Mitocondrias/metabolismo , Mutación , Alelos , Aminoacil-ARNt Sintetasas/química , Regulación Fúngica de la Expresión Génica , Genotipo , Proteínas Mitocondriales/genética , Proteínas Mitocondriales/metabolismo , Modelos Moleculares , Unión Proteica , Conformación Proteica , Transporte de Proteínas , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae , Transcripción Genética

RESUMEN

The origin and evolution of life on the planet is one of the most intriguing challenges in life sciences and, for some researchers, it is centered in the origin of the genetic code. Many hypotheses about the origin and evolution of tRNA have been proposed and in this work a new suggestion is proposed based on the reconstruction of tRNA ancestor sequences. Ancestral sequences of 22 types of tRNA molecules were built by maximum likelihood from 9758 sequences currently reported from different organisms. Phylogenetic analysis showed that the main force for evolutionary diversification of tRNA molecules was a change in the second base of the anticodon. The data revealed that diversification is not correlated with the characteristic of the specified amino acid, indicating that the correlation between tRNA and amino acid was given indirectly, and possibly should have been mediated by proto-aminoacyl-tRNA synthetases.

Asunto(s)

Anticodón/genética , Evolución Molecular , Modelos Genéticos , Filogenia , Aminoacil-ARNt Sintetasas/genética

RESUMEN

Bacterial GatCAB amidotransferases are responsible for the transamidation of mischarged glutamyl-tRNA(Gln) into glutaminyl-tRNA(Gln). Mitochondria matrix also has a multienzymatic complex necessary for the transamidation of glutamyl-tRNA(Gln). Gtf1p, Her2p and Pet112p are the constituents of mitochondrial GatFAB amidotransferase complex. Her2p is subunit A of GatFAB complex, while Gtf1p is subunit F, a connector protein between Pet112p (subunit B) and Her2p. Here we evaluate through molecular modeling and amino acid correlation analysis the HER2 protein family. Localization studies indicated that Her2p is predominantly localized in the mitochondrial outer membrane, but it is also located in the mitochondrial matrix where together with Pet112p and Gtf1p constitutes the GatFAB complex. Finally, HER2 random mutagenesis unveiled important residues that provide thermo stability for the complex and are differently suppressed by overexpression of GTF1 or PET112. For instance, her2/ts11 mutant showed its fermentative growth impaired, and poorly rescued by GTF1 indicating that Her2p unknown function in the mitochondria outer membrane affects cell viability.

Asunto(s)

Aminoacil-ARNt Sintetasas/genética , Mitocondrias/enzimología , Proteínas Mitocondriales/genética , Transferasas de Grupos Nitrogenados/genética , Transferasas de Grupos Nitrogenados/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Transaminasas/genética , Aminoacil-ARNt Sintetasas/metabolismo , Supervivencia Celular , Mapeo Cromosómico , Retículo Endoplásmico/metabolismo , Glutamina/genética , Mitocondrias/genética , Mitocondrias/metabolismo , Proteínas Mitocondriales/metabolismo , Modelos Moleculares , Mutación , Aminoacil-ARN de Transferencia/genética , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Alineación de Secuencia , Transaminasas/metabolismo

RESUMEN

BACKGROUND: Glutamyl queuosine-tRNA(Asp) synthetase (GluQ-RS) is a paralog of the catalytic domain of glutamyl-tRNA synthetase and catalyzes the formation of glutamyl-queuosine on the wobble position of tRNA(Asp). Here we analyze the transcription of its gene in Shigella flexneri, where it is found downstream of dksA, which encodes a transcriptional regulator involved in stress responses. RESULTS: The genomic organization, dksA-gluQ-rs, is conserved in more than 40 bacterial species. RT-PCR assays show co-transcription of both genes without a significant change in transcript levels during growth of S. flexneri. However, mRNA levels of the intergenic region changed during growth, increasing at stationary phase, indicating an additional level of control over the expression of gluQ-rs gene. Transcriptional fusions with lacZ as a reporter gene only produced ß-galactosidase activity when the constructs included the dksA promoter, indicating that gluQ-rs do not have a separate promoter. Using bioinformatics, we identified a putative transcriptional terminator between dksA and gluQ-rs. Deletion or alteration of the predicted terminator resulted in increased expression of the lacZ reporter compared with cells containing the wild type terminator sequence. Analysis of the phenotype of a gluQ-rs mutant suggested that it may play a role in some stress responses, since growth of the mutant was impaired in the presence of osmolytes. CONCLUSIONS: The results presented here, show that the expression of gluQ-rs depends on the dksA promoter, and strongly suggest the presence and the functionality of a transcriptional terminator regulating its expression. Also, the results indicate a link between glutamyl-queuosine synthesis and stress response in Shigella flexneri.

Asunto(s)

Aminoacil-ARNt Sintetasas/metabolismo , Proteínas Bacterianas/metabolismo , Regulación Bacteriana de la Expresión Génica , Shigella flexneri/genética , Shigella flexneri/metabolismo , Factores de Transcripción/metabolismo , Aminoacil-ARNt Sintetasas/genética , Fusión Artificial Génica , Proteínas Bacterianas/genética , Biología Computacional , Análisis Mutacional de ADN , Orden Génico , Genes Reporteros , Regiones Promotoras Genéticas , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Eliminación de Secuencia , Sintenía , Factores de Transcripción/genética , Terminación de la Transcripción Genética , beta-Galactosidasa/análisis , beta-Galactosidasa/genética

RESUMEN

The bacterial GatCAB operon for tRNA-dependent amidotransferase (AdT) catalyzes the transamidation of mischarged glutamyl-tRNA(Gln) to glutaminyl-tRNA(Gln). Here we describe the phenotype of temperature-sensitive (ts) mutants of GTF1, a gene proposed to code for subunit F of mitochondrial AdT in Saccharomyces cerevisiae. The ts gtf1 mutants accumulate an electrophoretic variant of the mitochondrially encoded Cox2p subunit of cytochrome oxidase and an unstable form of the Atp8p subunit of the F(1)-F(0) ATP synthase that is degraded, thereby preventing assembly of the F(0) sector. Allotopic expression of recoded ATP8 and COX2 did not significantly improve growth of gtf1 mutants on respiratory substrates. However, ts gft1 mutants are partially rescued by overexpression of PET112 and HER2 that code for the yeast homologues of the catalytic subunits of bacterial AdT. Additionally, B66, a her2 point mutant has a phenotype similar to that of gtf1 mutants. These results provide genetic support for the essentiality, in vivo, of the GatF subunit of the heterotrimeric AdT that catalyzes formation of glutaminyl-tRNA(Gln) (Frechin, M., Senger, B., Brayé, M., Kern, D., Martin, R. P., and Becker, H. D. (2009) Genes Dev. 23, 1119-1130).

Asunto(s)

Aminoacil-ARNt Sintetasas/metabolismo , Mitocondrias/enzimología , Transferasas de Grupos Nitrogenados/metabolismo , Subunidades de Proteína/metabolismo , ARN de Transferencia/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/enzimología , Adenosina Trifosfatasas/metabolismo , Secuencia de Aminoácidos , Antimicina A/análogos & derivados , Antimicina A/farmacología , Regulación Fúngica de la Expresión Génica/efectos de los fármacos , Genes Mitocondriales/genética , Mitocondrias/efectos de los fármacos , Mitocondrias/genética , Mutación/genética , NADH Deshidrogenasa/metabolismo , Péptidos/química , Fenotipo , Biosíntesis de Proteínas/efectos de los fármacos , Transporte de Proteínas/efectos de los fármacos , ARN Mensajero/genética , ARN Mensajero/metabolismo , Saccharomyces cerevisiae/citología , Saccharomyces cerevisiae/efectos de los fármacos , Saccharomyces cerevisiae/genética , Temperatura

RESUMEN

We critically examine the proposal by Wächtershäuser (Prokaryotes 1:275-283, 2006a, Philos Trans R Soc Lond B Biol Sci 361: 787-1808, 2006b) that putative transition metal binding sites in protein components of the translation machinery of hyperthermophiles provide evidence of a direct relationship with the FeS clusters of pyrite and thus indicate an autotrophic origin of life in volcanic environments. Analysis of completely sequenced cellular genomes of Bacteria, Archaea and Eucarya does not support the suggestion by Wächtershäuser (Prokaryotes 1:275-283, 2006a, Philos Trans R Soc Lond B Biol Sci 361: 787-1808, 2006b) that aminoacyl-tRNA synthetases and ribosomal proteins bear sequence signatures typical of strong covalent metal bonding whose absence in mesophilic species reveals a process of adaptation towards less extreme environments.

Asunto(s)

Aminoacil-ARNt Sintetasas/metabolismo , Coenzimas/metabolismo , Hierro/metabolismo , Metaloproteínas/metabolismo , Origen de la Vida , Sulfuros/metabolismo , Aminoacil-ARNt Sintetasas/genética , Cationes Bivalentes/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo , Genoma Arqueal , Genoma Bacteriano , Methanococcales/genética , Methanococcales/metabolismo , Proteínas Ribosómicas/genética , Proteínas Ribosómicas/metabolismo , Zinc/metabolismo , Dedos de Zinc