RESUMEN
CelTOS is a malaria vaccine antigen that is conserved in Plasmodium and other apicomplexan parasites and plays a role in cell-traversal. The structural basis and mechanisms of CelTOS-induced protective immunity to parasites are unknown. Here, CelTOS-specific monoclonal antibodies (mAbs) 7g7 and 4h12 demonstrated multistage activity, protecting against liver infection and preventing parasite transmission to mosquitoes. Both mAbs demonstrated cross-species activity with sterile protection against in vivo challenge with transgenic parasites containing either P. falciparum or P. vivax CelTOS, and with transmission reducing activity against P. falciparum. The mAbs prevented CelTOS-mediated pore formation providing insight into the protective mechanisms. X-ray crystallography and mutant-library epitope mapping revealed two distinct broadly conserved neutralizing epitopes. 7g7 bound to a parallel dimer of CelTOS, while 4h12 bound to a novel antiparallel dimer architecture. These findings inform the design of antibody therapies and vaccines and raise the prospect of a single intervention to simultaneously combat P. falciparum and P. vivax malaria.
Asunto(s)
Anticuerpos Monoclonales , Anticuerpos Antiprotozoarios , Vacunas contra la Malaria , Plasmodium falciparum , Plasmodium vivax , Anticuerpos Monoclonales/inmunología , Animales , Plasmodium falciparum/inmunología , Plasmodium vivax/inmunología , Vacunas contra la Malaria/inmunología , Anticuerpos Antiprotozoarios/inmunología , Ratones , Malaria Falciparum/inmunología , Malaria Falciparum/prevención & control , Malaria Falciparum/parasitología , Cristalografía por Rayos X , Epítopos/inmunología , Malaria Vivax/prevención & control , Malaria Vivax/inmunología , Malaria Vivax/parasitología , Antígenos de Protozoos/inmunología , Humanos , Femenino , Mapeo Epitopo , Malaria/inmunología , Malaria/prevención & control , Malaria/parasitología , Ratones Endogámicos BALB C , Proteínas Protozoarias/inmunología , Proteínas Protozoarias/químicaRESUMEN
The direct synthesis of alkenes from alkynes usually requires the use of transition-metal catalysts. Unfortunately, efficient biocatalytic alternatives for this transformation have yet to be discovered. Herein, the selective bioreduction of electron-deficient alkynes to alkenes catalysed by ene-reductases (EREDs) is described. Alkynes bearing ketone, aldehyde, ester, and nitrile moieties have been effectively reduced with excellent conversions and stereoselectivities, observing clear trends for the E/Z ratios depending on the nature of the electron-withdrawing group. In the case of cyanoalkynes, (Z)-alkenes were obtained as the major product, and the reaction scope was expanded to a wide variety of aromatic substrates (up to >99 % conversion, and Z/E stereoselectivities of up to >99/1). Other alkynes containing aldehyde, ketone, or ester functionalities also proved to be excellent substrates, and interestingly gave the corresponding (E)-alkenes. Preparative biotransformations were performed on a 0.4â mmol scale, producing the desired (Z)-cyanoalkenes with good to excellent isolated yields (63-97 %). This novel reactivity has been rationalised through molecular docking by predicting the binding poses of key molecules in the ERED-pu-0006 active site.
RESUMEN
Tetracycline destructases (TDases) are flavin monooxygenases which can confer resistance to all generations of tetracycline antibiotics. The recent increase in the number and diversity of reported TDase sequences enables a deep investigation of the TDase sequence-structure-function landscape. Here, we evaluate the sequence determinants of TDase function through two complementary approaches: (1) constructing profile hidden Markov models to predict new TDases, and (2) using multiple sequence alignments to identify conserved positions important to protein function. Using the HMM-based approach we screened 50 high-scoring candidate sequences in Escherichia coli, leading to the discovery of 13 new TDases. The X-ray crystal structures of two new enzymes from Legionella species were determined, and the ability of anhydrotetracycline to inhibit their tetracycline-inactivating activity was confirmed. Using the MSA-based approach we identified 31 amino acid positions 100% conserved across all known TDase sequences. The roles of these positions were analyzed by alanine-scanning mutagenesis in two TDases, to study the impact on cell and in vitro activity, structure, and stability. These results expand the diversity of TDase sequences and provide valuable insights into the roles of important residues in TDases, and flavin monooxygenases more broadly.
Asunto(s)
Antibacterianos , Tetraciclina , Tetraciclina/farmacología , Antibacterianos/farmacología , Antibacterianos/química , Tetraciclinas/farmacología , Oxigenasas de Función Mixta , Escherichia coli/química , Farmacorresistencia Microbiana , FlavinasRESUMEN
Immunoglobulin-degrading proteases are secreted by pathogenic bacteria to weaken the host immune response, contributing to immune evasion mechanisms during an infection. Proteases specific to IgG and IgA immunoglobulin classes have previously been identified and characterized, and only a single report exists on a porcine specific IgM-degrading enzyme. It is unclear whether human pathogens also produce enzymes that can break down human IgM. Here, we have identified four novel IgM-degrading proteases from different genera of human-infecting bacterial pathogens. All four protease domains cleave human IgM at a conserved and unique site in the constant region of IgM. These human IgM proteases may be a useful biochemical tool for the study of early immune responses and have therapeutic potential in IgM-mediated disease.
Asunto(s)
Bacterias , Proteínas Bacterianas , Humanos , Animales , Porcinos , Proteínas Bacterianas/química , Endopeptidasas , Péptido Hidrolasas , Inmunoglobulina MRESUMEN
Inactivation of tetracycline antibiotics by tetracycline destructases (TDases) remains a clinical and agricultural threat. TDases can be classified as type 1 Tet(X)-like TDases and type 2 soil-derived TDases. Type 1 TDases are widely identified in clinical pathogens. A combination therapy of tetracycline and a TDase inhibitor is much needed to rescue the clinical efficacy of tetracyclines. Anhydrotetracycline is a pan-TDase inhibitor that inhibits both type 1 and type 2 TDases. Here, we present structural, biochemical, and phenotypic evidence that anhydrotetracycline binds in a substrate-like orientation and competitively inhibits the type 1 TDase Tet(X6) to rescue tetracycline antibiotic activity as a sacrificial substrate. Anhydrotetracycline interacting residues of Tet(X6) are conserved within type 1 TDases, indicating a conserved binding mode and mechanism of inhibition. This mode of binding and inhibition is distinct from anhydrotetracycline's inhibition of type 2 TDases. This study forms the framework for development of next-generation therapies to counteract enzymatic tetracycline resistance.
Asunto(s)
Tetraciclina , Tetraciclinas , Tetraciclina/farmacología , Tetraciclinas/farmacología , Antibacterianos/farmacología , Antibacterianos/químicaRESUMEN
A new species, Euconocephalus narayanpurensis Kumar & Chand sp. nov., from India is described in this paper. The new species is similar to the African species Euconocephalus lineatipes (Bolívar, 1890), but differs from the latter in the smaller size, more acute humeral sinus, the narrowly rounded apex of elytra and convex male last abdominal tergite. A key to the Indian species of Euconocephalus Karny, 1907 is also provided.
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Ortópteros , Masculino , Animales , Distribución Animal , IndiaRESUMEN
Tetracyclines (TCs) are an important class of antibiotics threatened by an emerging new resistance mechanismâenzymatic inactivation. These TC-inactivating enzymes, also known as tetracycline destructases (TDases), inactivate all known TC antibiotics, including drugs of last resort. Combination therapies consisting of a TDase inhibitor and a TC antibiotic represent an attractive strategy for overcoming this type of antibiotic resistance. Here, we report the structure-based design, synthesis, and evaluation of bifunctional TDase inhibitors derived from anhydrotetracycline (aTC). By appending a nicotinamide isostere to the C9 position of the aTC D-ring, we generated bisubstrate TDase inhibitors. The bisubstrate inhibitors have extended interactions with TDases by spanning both the TC and presumed NADPH binding pockets. This simultaneously blocks TC binding and the reduction of FAD by NADPH while "locking" TDases in an unproductive FAD "out" conformation.
Asunto(s)
Compuestos Heterocíclicos , Tetraciclina , Tetraciclina/farmacología , Tetraciclina/metabolismo , NADP/metabolismo , Antibacterianos/farmacología , Antibacterianos/química , Tetraciclinas/farmacología , Inhibidores de la Síntesis de la Proteína , Oxidación-ReducciónRESUMEN
A new species, Xestophrys bengalensis sp. nov., from the West Bengal state of India is described in this paper. The new species is superficially similar to the Indonesian species Xestophrys javanicus lombockensis Carl, 1908, but differs from the latter in the smaller size, anterior femur unarmed on the external margin, and hind femur with two spines on the internal margin. A key to the species of Xestophrys Redtenbacher, 1891 is also provided.
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Ortópteros , Animales , Distribución Animal , IndiaRESUMEN
Malaria and other apicomplexan-caused diseases affect millions of humans, agricultural animals, and pets. Cell traversal is a common feature used by multiple apicomplexan parasites to migrate through host cells and can be exploited to develop therapeutics against these deadly parasites. Here, we provide insights into the mechanism of the Cell-traversal protein for ookinetes and sporozoites (CelTOS), a conserved cell-traversal protein in apicomplexan parasites and malaria vaccine candidate. CelTOS has previously been shown to form pores in cell membranes to enable traversal of parasites through cells. We establish roles for the distinct protein regions of Plasmodium vivax CelTOS and examine the mechanism of pore formation. We further demonstrate that CelTOS dimer dissociation is required for pore formation, as disulfide bridging between monomers inhibits pore formation, and this inhibition is rescued by disulfide-bridge reduction. We also show that a helix-destabilizing amino acid, Pro127, allows CelTOS to undergo significant conformational changes to assemble into pores. The flexible C terminus of CelTOS is a negative regulator that limits pore formation. Finally, we highlight that lipid binding is a prerequisite for pore assembly as mutation of a phospholipids-binding site in CelTOS resulted in loss of lipid binding and abrogated pore formation. These findings identify critical regions in CelTOS and will aid in understanding the egress mechanism of malaria and other apicomplexan parasites as well as have implications for studying the function of other essential pore-forming proteins.
Asunto(s)
Vacunas contra la Malaria , Malaria Vivax , Plasmodium vivax , Proteínas Protozoarias , Sitios de Unión , Disulfuros/química , Humanos , Vacunas contra la Malaria/química , Vacunas contra la Malaria/genética , Vacunas contra la Malaria/inmunología , Malaria Vivax/prevención & control , Fosfolípidos/inmunología , Plasmodium vivax/genética , Plasmodium vivax/inmunología , Prolina/química , Prolina/genética , Conformación Proteica en Hélice alfa , Multimerización de Proteína , Proteínas Protozoarias/química , Proteínas Protozoarias/genética , Proteínas Protozoarias/inmunología , Esporozoítos/genética , Esporozoítos/inmunologíaRESUMEN
More than one hundred years after its description, a male specimen of Liara(Unalianus)heteracanthus(Redtenbacher, 1891) was collected at a new locality in the Mizoram State, India. Opportunity is taken to redescribe and illustrate this specimen.
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Ortópteros , Distribución Animal , Animales , India , MasculinoRESUMEN
In the context of Indian zoogeography, the DNA barcode data of short-horned grasshoppers (family Acrididae) are limited in global databases. Hence, the present study was aimed to collect selected Acridid species from the Indian Himalayan regions and generate DNA barcode data to enrich the global database. The estimated K2P genetic distances, Bayesian analysis (BA) topology and multiple species delimitation methods (ABGD, bPTP, and GMYC) clearly discriminate all the studied species. Based on high genetic distance (7.5%), multiple clades, and more than one molecular operational taxonomic unit, the present study elucidates the allopatric speciation and presence of possible cryptic diversity of Oxya japonica within India, China, and Russia. The present study suggests the collection of multiple specimens from different geographical locations and the generation of more DNA barcode data would facilitate the actual diversity of this insect group.
RESUMEN
Tetracycline resistance by antibiotic inactivation was first identified in commensal organisms but has since been reported in environmental and pathogenic microbes. Here, we identify and characterize an expanded pool of tet(X)-like genes in environmental and human commensal metagenomes via inactivation by antibiotic selection of metagenomic libraries. These genes formed two distinct clades according to habitat of origin, and resistance phenotypes were similarly correlated. Each gene isolated from the human gut encodes resistance to all tetracyclines tested, including eravacycline and omadacycline. We report a biochemical and structural characterization of one enzyme, Tet(X7). Further, we identify Tet(X7) in a clinical Pseudomonas aeruginosa isolate and demonstrate its contribution to tetracycline resistance. Lastly, we show anhydrotetracycline and semi-synthetic analogues inhibit Tet(X7) to prevent enzymatic tetracycline degradation and increase tetracycline efficacy against strains expressing tet(X7). This work improves our understanding of resistance by tetracycline-inactivation and provides the foundation for an inhibition-based strategy for countering resistance.
Asunto(s)
Antibacterianos/farmacología , Pseudomonas aeruginosa/enzimología , Resistencia a la Tetraciclina/genética , Tetraciclinas/antagonistas & inhibidores , Interacciones Huésped-Patógeno , Humanos , Pruebas de Sensibilidad Microbiana , Pseudomonas aeruginosa/efectos de los fármacos , SimbiosisRESUMEN
Female of Letana mursinga Ingrisch Shishodia, 2000 is described first time from Arunachal Pradesh, India along with a checklist of Indian species of Letana Walker, 1869. A map is also prepared for its distribution.
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Ortópteros , Distribución Animal , Animales , Femenino , IndiaRESUMEN
Orthelimaea himalayana (Ingrisch, 1990) is recorded for the first time from India and its female is also described first time from Central Himalaya. A key to Indian species of Orthelimaea Karny, 1926 is also provided.
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Ortópteros , Animales , Femenino , IndiaRESUMEN
A new species of the genus Anaptygus Mistshenko, 1951, Anaptygus shishodiai Kumar Chandra sp. nov., from Valley of Flowers National Park, India is described in this paper. The new species is similar to A. qinghaiensis Yin, 1984, but differs from latter by length of fastigial foveolae 5.5 times its width in male and 3.2 times in female; apex of elytra reaching posterior margin of third abdominal tergite in male and reaching posterior margin of first abdominal tergite in female. A key to all the known species of Anaptygus Mistshenko, 1951 is also provided.
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Saltamontes , Ortópteros , Distribución Animal , Estructuras Animales , Animales , Tamaño Corporal , Ambiente , Femenino , India , Masculino , Tamaño de los Órganos , Parques RecreativosRESUMEN
During transmission of malaria-causing parasites from mosquito to mammal, Plasmodium sporozoites migrate at high speed within the skin to access the bloodstream and infect the liver. This unusual gliding motility is based on retrograde flow of membrane proteins and highly dynamic actin filaments that provide short tracks for a myosin motor. Using laser tweezers and parasite mutants, we previously suggested that actin filaments form macromolecular complexes with plasma membrane-spanning adhesins to generate force during migration. Mutations in the actin-binding region of profilin, a near ubiquitous actin-binding protein, revealed that loss of actin binding also correlates with loss of force production and motility. Here, we show that different mutations in profilin, that do not affect actin binding in vitro, still generate lower force during Plasmodium sporozoite migration. Lower force generation inversely correlates with increased retrograde flow suggesting that, like in mammalian cells, the slow down of flow to generate force is the key underlying principle governing Plasmodium gliding motility.
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Malaria , Parásitos , Actinas/genética , Animales , Plasmodium berghei , Profilinas/genética , Proteínas Protozoarias/genéticaRESUMEN
In the present paper a new species, Xestophrys namtseringa Kumar Chandra sp. nov. is described and illustrated from Indian Himalaya. Key to all the known species of Xestophrys Redtenbacher, 1891 is also provided. [Zoobank URL: urn:lsid:zoobank.org:act:C18B59A4-30F8-4753-8739-6482D7F5A6B2].
Asunto(s)
Ortópteros , Distribución Animal , Animales , IndiaAsunto(s)
Malaria Falciparum/metabolismo , Malaria Vivax/metabolismo , Malaria/metabolismo , Animales , Anopheles/patogenicidad , Humanos , Insectos Vectores , Malaria/genética , Plasmodium falciparum/metabolismo , Plasmodium falciparum/patogenicidad , Plasmodium vivax/metabolismo , Plasmodium vivax/patogenicidadRESUMEN
The synthesis and biological evaluation of semisynthetic anhydrotetracycline analogues as small molecule inhibitors of tetracycline-inactivating enzymes are reported. Inhibitor potency was found to vary as a function of enzyme (major) and substrate-inhibitor pair (minor), and anhydrotetracycline analogue stability to enzymatic and nonenzymatic degradation in solution contributes to their ability to rescue tetracycline activity in whole cell Escherichia coli expressing tetracycline destructase enzymes. Taken collectively, these results provide the framework for the rational design of next-generation inhibitor libraries en route to a viable and proactive adjuvant approach to combat the enzymatic degradation of tetracycline antibiotics.