RESUMO
MOTIVATION: With the increasing availability of 3D-data, the focus of comparative bioinformatic analysis is shifting from protein sequence alignments toward more content-rich 3D-alignments. This raises the need for new ways to improve the accuracy of 3D-superimposition. RESULTS: We proposed guide tree optimization with genetic algorithm (GA) as a universal tool to improve the alignment quality of multiple protein 3D-structures systematically. As a proof of concept, we implemented the suggested GA-based approach in popular Matt and Caretta multiple protein 3D-structure alignment (M3DSA) algorithms, leading to a statistically significant improvement of the TM-score quality indicator by up to 220-1523% on 'SABmark Superfamilies' (in 49-77% of cases) and 'SABmark Twilight' (in 59-80% of cases) datasets. The observed improvement in collections of distant homologies highlights the potentials of GA to optimize 3D-alignments of diverse protein superfamilies as one plausible tool to study the structure-function relationship. AVAILABILITY AND IMPLEMENTATION: The source codes of patched gaCaretta and gaMatt programs are available open-access at https://github.com/n-canter/gamaps. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.
Assuntos
Proteínas , Software , Proteínas/química , Algoritmos , Alinhamento de SequênciaRESUMO
Zebra2 is a highly automated web-tool to search for subfamily-specific and conserved positions (i.e. the determinants of functional diversity as well as the key catalytic and structural residues) in protein superfamilies. The bioinformatic analysis is facilitated by Mustguseal-a companion web-server to automatically collect and superimpose a large representative set of functionally diverse homologs with high structure similarity but low sequence identity to the selected query protein. The results are automatically prioritized and provided at four information levels to facilitate the knowledge-driven expert selection of the most promising positions on-line: as a sequence similarity network; interfaces to sequence-based and 3D-structure-based analysis of conservation and variability; and accompanied by the detailed annotation of proteins accumulated from the integrated databases with links to the external resources. The integration of Zebra2 and Mustguseal web-tools provides the first of its kind out-of-the-box open-access solution to conduct a systematic analysis of evolutionarily related proteins implementing different functions within a shared 3D-structure of the superfamily, determine common and specific patterns of function-associated local structural elements, assist to select hot-spots for rational design and to prepare focused libraries for directed evolution. The web-servers are free and open to all users at https://biokinet.belozersky.msu.ru/zebra2, no login required.
Assuntos
Alinhamento de Sequência , Análise de Sequência de Proteína/métodos , Software , Algoritmos , Sequência de Aminoácidos , Biologia Computacional/métodos , Sequência Conservada , Internet , Conformação Proteica , Proteínas/química , Proteínas/classificação , Homologia de Sequência de AminoácidosRESUMO
Disulfide bonds play a significant role in protein stability, function or regulation but are poorly conserved among evolutionarily related proteins. The Yosshi can help to understand the role of S-S bonds by comparing sequences and structures of homologs with diverse properties and different disulfide connectivity patterns within a common structural fold of a superfamily, and assist to select the most promising hot-spots to improve stability of proteins/enzymes or modulate their functions by introducing naturally occurring crosslinks. The bioinformatic analysis is supported by the integrated Mustguseal web-server to construct large structure-guided sequence alignments of functionally diverse protein families that can include thousands of proteins based on all available information in public databases. The Yosshi+Mustguseal is a new integrated web-tool for a systematic homology-driven analysis and engineering of S-S bonds that facilitates a broader interpretation of disulfides not just as a factor of structural stability, but rather as a mechanism to implement functional diversity within a superfamily. The results can be downloaded as a content-rich PyMol session file or further studied online using the HTML5-based interactive analysis tools. Both web-servers are free and open to all users at https://biokinet.belozersky.msu.ru/yosshi and there is no login requirement.
Assuntos
Algoritmos , Biologia Computacional/métodos , Dissulfetos/química , Proteínas/química , Software , Sequência de Aminoácidos , Internet , Modelos Moleculares , Engenharia de Proteínas , Alinhamento de SequênciaRESUMO
MOTIVATION: Accurate structural alignment of proteins is crucial at studying structure-function relationship in evolutionarily distant homologues. Various software tools were proposed to align multiple protein 3D-structures utilizing one CPU and thus are of limited productivity at large-scale analysis of protein families/superfamilies. RESULTS: The parMATT is a hybrid MPI/pthreads/OpenMP parallel re-implementation of the MATT algorithm to align multiple protein 3D-structures by allowing translations and twists. The parMATT can be faster than MATT on a single multi-core CPU, and provides a much greater speedup when executed on distributed-memory systems, i.e. computing clusters and supercomputers hosting memory-independent computing nodes. The most computationally demanding steps of the MATT algorithm-the initial construction of pairwise alignments between all input structures and further iterative progression of the multiple alignment-were parallelized using MPI and pthreads, and the concluding refinement step was optimized by introducing the OpenMP support. The parMATT can significantly accelerate the time-consuming process of building a multiple structural alignment from a large set of 3D-records of homologous proteins. AVAILABILITY AND IMPLEMENTATION: The source code is available at https://biokinet.belozersky.msu.ru/parMATT. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.
Assuntos
Software , Algoritmos , Redes de Comunicação de Computadores , Conformação Proteica , Proteínas , Alinhamento de SequênciaRESUMO
The ability of ligands to form crucial interactions with a protein target, characteristic for the substrate and/or inhibitors, could be considered a structural criterion for identifying potent binders among docked compounds. Structural filtration of predicted poses improves the performance of virtual screening and helps in recovering specifically bound ligands. Here, we present vsFilt-a highly automated and easy-to-use Web server for postdocking structural filtration. The new tool can detect various types of interactions that are known to be involved in the molecular recognition, including hydrogen and halogen bonds, ionic interactions, hydrophobic contacts, π-stacking, and cation-π interactions. A case study for poly(ADP-ribose) polymerase 1 ligands illustrates the utility of the software. The Web server is freely available at https://biokinet.belozersky.msu.ru/vsfilt.
Assuntos
Proteínas , Software , Sítios de Ligação , Computadores , Ligantes , Simulação de Acoplamento Molecular , Ligação Proteica , Proteínas/metabolismoRESUMO
Motivation: Comparative analysis of homologous proteins in a functionally diverse superfamily is a valuable tool at studying structure-function relationship, but represents a methodological challenge. Results: The Mustguseal web-server can automatically build large structure-guided sequence alignments of functionally diverse protein families that include thousands of proteins basing on all available information about their structures and sequences in public databases. Superimposition of protein structures is implemented to compare evolutionarily distant relatives, whereas alignment of sequences is used to compare close homologues. The final alignment can be downloaded for a local use or operated on-line with the built-in interactive tools and further submitted to the integrated sister web-servers of Mustguseal to analyze conserved, subfamily-specific and co-evolving residues at studying a protein function and regulation, designing improved enzyme variants for practical applications and selective ligands to modulate functional properties of proteins. Availability and implementation: Freely available on the web at https://biokinet.belozersky.msu.ru/mustguseal. Contact: vytas@belozersky.msu.ru. Supplementary information: Supplementary data are available at Bioinformatics online.
Assuntos
Proteínas/química , Alinhamento de Sequência , Computadores , Ligantes , Modelos Moleculares , Estrutura Terciária de Proteína , SoftwareRESUMO
PLP-Dependent fold-type IV branched-chain amino acid aminotransferases (BCATs) from archaea have so far been poorly characterized. A new BCAT from the hyperthermophilic archaeon Thermoproteus uzoniensis (TUZN1299) has been studied. TUZN1299 was found to be highly active toward branched-chain amino acids (BCAAs), positively charged amino acids, l-methionine, l-threonine, l-homoserine, l-glutamine, as well as toward 2-oxobutyrate and keto analogs of BCAAs, whereas l-glutamate and α-ketoglutarate were not converted in the overall reaction. According to stopped-flow experiments, the enzyme showed the highest specificity to BCAAs and their keto analogs. In order to explain the molecular mechanism of the unusual specificity of TUZN1299, bioinformatic analysis was implemented to identify the subfamily-specific positions in the aminotransferase class IV superfamily of enzymes. The role of the selected residues in binding of various ligands in the active site was further studied using molecular modeling. The results indicate that Glu188 forms a novel binding site for positively charged and polar side-chains of amino acids. Lack of accommodation for α-ketoglutarate and l-glutamate is due to the unique orientation and chemical properties of residues 102-106 in the loop forming the A-pocket. The likely functional roles of TUZN1299 in cellular metabolism - in the synthesis and degradation of BCAAs - are discussed.
Assuntos
Aminoácidos de Cadeia Ramificada/química , Biologia Computacional/métodos , Thermoproteus/enzimologia , Transaminases/química , Sítios de Ligação , Simulação por Computador , Cristalografia por Raios X , Glutamina/química , Concentração de Íons de Hidrogênio , Cinética , Modelos Moleculares , Ligação Proteica , Conformação Proteica , Especificidade por SubstratoRESUMO
The new web-server pocketZebra implements the power of bioinformatics and geometry-based structural approaches to identify and rank subfamily-specific binding sites in proteins by functional significance, and select particular positions in the structure that determine selective accommodation of ligands. A new scoring function has been developed to annotate binding sites by the presence of the subfamily-specific positions in diverse protein families. pocketZebra web-server has multiple input modes to meet the needs of users with different experience in bioinformatics. The server provides on-site visualization of the results as well as off-line version of the output in annotated text format and as PyMol sessions ready for structural analysis. pocketZebra can be used to study structure-function relationship and regulation in large protein superfamilies, classify functionally important binding sites and annotate proteins with unknown function. The server can be used to engineer ligand-binding sites and allosteric regulation of enzymes, or implemented in a drug discovery process to search for potential molecular targets and novel selective inhibitors/effectors. The server, documentation and examples are freely available at http://biokinet.belozersky.msu.ru/pocketzebra and there are no login requirements.
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Proteínas/metabolismo , Software , Algoritmos , Sítios de Ligação , Biologia Computacional , Internet , Ligantes , Proteínas/química , Proteínas/classificação , Alinhamento de SequênciaRESUMO
Neuraminidase A from Streptococcus pneumoniae (NanA) is considered a potentially key pathogenicity factor and a promising drug target to treat human infectious diseases. Computational and experimental efforts are increasingly being used to study its structure and function which yet remain poorly understood. In this work, we characterized structural dynamics of NanA's active site and gained novel mechanistic insights into its implications for a ligand binding. We based our study on supercomputer modeling and bioinformatic analysis with a help of crystallographic data and by bringing together previously published experimental data. The most prominent conformational plasticity was observed in the loop 422-437, accompanied by the mobility of adjacent loops 352-360 and 579-587. These structural elements had been undergoing spontaneous fluctuations apparently playing the role of an active site lid: an "open" state allowed substrate access to the active site, while a "closed" state accommodated the substrate in a catalytically favorable orientation. We observed that conformational plasticity of the loop 422-437 promoted the formation of an additional pocket located between catalytic and insertion domains of the enzyme. We recently argued this site was able to bind isoprenylated flavone artocarpin as an inhibitor of pneumococcal biofilm formation. Here we showed that accommodation of the mixed-type inhibitor artocarpin in this pocket limited mobility of the loop 422-437. This represents a plausible explanation of artocarpin's regulatory effect on the enzyme's catalytic function which seems to be independent of its role in preventing biofilm formation.
Assuntos
Neuraminidase , Streptococcus pneumoniae , Regulação Alostérica , Domínio Catalítico , Humanos , Neuraminidase/química , Neuraminidase/metabolismo , Streptococcus pneumoniae/fisiologiaRESUMO
Neuraminidase A from Streptococcus pneumoniae (NanA) is a cell wall-bound modular enzyme containing one lectin and one catalytic domain. Unlike homologous NanB and NanC expressed by the same bacterium, the two domains within one NanA molecule do not form a stable interaction and are spatially separated by a 16-amino acid-long flexible linker. In this work, the ability of NanA to form intermolecular assemblies was characterized using the methods of molecular modeling and bioinformatic analysis based on crystallographic data and by bringing together previously published experimental data. It was concluded that two catalytic domains, as well as one catalytic and one lectin domain, originating from two cell wall-bound NanA molecules, can interact through a previously uncharacterized interdomain interface to form complexes stabilized by a network of intermolecular hydrogen bonds and salt bridges. Supercomputer modeling strongly indicated that artocarpin, an earlier experimentally discovered inhibitor of the pneumococcal biofilm formation, is able to bind to a site located in the catalytic domain of one NanA entity and prevent its interaction with the lectin or catalytic domain of another NanA entity, thus directly precluding the generation of intermolecular assemblies. The revealed structural adaptation is discussed as one plausible mechanism of noncatalytic participation of this potentially key pathogenicity enzyme in pneumococcal biofilm formation.
Assuntos
Antibacterianos/química , Proteínas de Bactérias/química , Glicosídeos/química , Lectinas de Ligação a Manose/química , Neuraminidase/química , Lectinas de Plantas/química , Streptococcus pneumoniae/enzimologia , Sequência de Aminoácidos , Antibacterianos/farmacologia , Proteínas de Bactérias/antagonistas & inibidores , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Biofilmes/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , Domínio Catalítico , Biologia Computacional/métodos , Expressão Gênica , Glicosídeos/metabolismo , Ligação de Hidrogênio , Cinética , Lectinas de Ligação a Manose/farmacologia , Modelos Moleculares , Neuraminidase/antagonistas & inibidores , Neuraminidase/genética , Neuraminidase/metabolismo , Lectinas de Plantas/farmacologia , Ligação Proteica , Conformação Proteica em alfa-Hélice , Conformação Proteica em Folha beta , Domínios e Motivos de Interação entre Proteínas , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Streptococcus pneumoniae/efeitos dos fármacos , Streptococcus pneumoniae/crescimento & desenvolvimento , Especificidade por Substrato , TermodinâmicaRESUMO
Bioinformatic analysis of functionally diverse superfamilies can help to study the structure-function relationship in proteins, but represents a methodological challenge. The Mustguseal web-server can build large structure-guided sequence alignments of thousands of homologs that cover all currently available sequence variants within a common structural fold. The input to the method is a PDB code of the query protein, which represents the protein superfamily of interest. The collection and subsequent alignment of protein sequences and structures is fully automated and driven by the particular choice of parameters. Four integrated sister web-methods-the Zebra, pocketZebra, visualCMAT, and Yosshi-are available to further analyze the resulting superimposition and identify conserved, subfamily-specific, and co-evolving residues, as well as to classify and study disulfide bonds in protein superfamilies. The integration of these web-based bioinformatic tools provides an out-of-the-box easy-to-use solution, first of its kind, to study protein function and regulation and design improved enzyme variants for practical applications and selective ligands to modulate their functional properties. In this chapter, we provide a step-by-step protocol for a comprehensive bioinformatic analysis of a protein superfamily using a web-browser as the main tool and notes on selecting the appropriate values for the key algorithm parameters depending on your research objective. The web-servers are freely available to all users at https://biokinet.belozersky.msu.ru/m-platform with no login requirement.
Assuntos
Biologia Computacional/métodos , Proteínas/química , Alinhamento de Sequência/métodos , Software , Algoritmos , Sequência de Aminoácidos , Biologia Computacional/instrumentação , Dissulfetos/química , Internet , Ligantes , Estrutura Terciária de Proteína , Alinhamento de Sequência/instrumentaçãoRESUMO
Local 3D-structural differences in homologous proteins contribute to functional diversity observed in a superfamily, but so far received little attention as bioinformatic analysis was usually carried out at the level of amino acid sequences. We have developed Zebra3D - the first-of-its-kind bioinformatic software for systematic analysis of 3D-alignments of protein families using machine learning. The new tool identifies subfamily-specific regions (SSRs) - patterns of local 3D-structure (i.e. single residues, loops, or secondary structure fragments) that are spatially equivalent within families/subfamilies, but are different among them, and thus can be associated with functional diversity and function-related conformational plasticity. Bioinformatic analysis of protein superfamilies by Zebra3D can be used to study 3D-determinants of catalytic activity and specific accommodation of ligands, help to prepare focused libraries for directed evolution or assist development of chimeric enzymes with novel properties by exchange of equivalent regions between homologs, and to characterize plasticity in binding sites. A companion Mustguseal web-server is available to automatically construct a 3D-alignment of functionally diverse proteins, thus reducing the minimal input required to operate Zebra3D to a single PDB code. The Zebra3D + Mustguseal combined approach provides the opportunity to systematically explore the value of SSRs in superfamilies and to use this information for protein design and drug discovery. The software is available open-access at https://biokinet.belozersky.msu.ru/Zebra3D.
RESUMO
The PARP family consists of 17 members with diverse functions, including those related to cancer cells' viability. Several PARP inhibitors are of great interest as innovative anticancer drugs, but they have low selectivity towards distinct PARP family members and exert serious adverse effects. We describe a family-wide study of the nicotinamide (NA) binding site, an important functional region in the PARP structure, using comparative bioinformatic analysis and molecular modeling. Mutations in the NA site and D-loop mobility around the NA site were identified as factors that can guide the design of selective PARP inhibitors. Our findings are of particular importance for the development of novel tankyrase (PARPs 5a and 5b) inhibitors for cancer therapy.
RESUMO
Creating biocatalysts for (R)-selective amination effectively is highly desirable in organic synthesis. Despite noticeable progress in the engineering of (R)-amine activity in pyridoxal-5'-phosphate-dependent transaminases of fold type IV, the specialization of the activity is still an intuitive task, as there is poor understanding of sequence-structure-function relationships. In this study, we analyzed this relationship in transaminase from Thermobaculum terrenum, distinguished by expanded substrate specificity and activity in reactions with L-amino acids and (R)-(+)-1-phenylethylamine using α-ketoglutarate and pyruvate as amino acceptors. We performed site-directed mutagenesis to create a panel of the enzyme variants, which differ in the active site residues from the parent enzyme to a putative transaminase specific to (R)-primary amines. The variants were examined in the overall transamination reactions and half-reaction with (R)-(+)-1-phenylethylamine. A structural analysis of the most prominent variants revealed a spatial reorganization in the active sites, which caused changes in activity. Although the specialization to (R)-amine transaminase was not implemented, we succeeded in understanding the role of the particular active site residues in expanding substrate specificity of the enzyme. We showed that the specificity for (R)-(+)-1-phenylethylamine in transaminase from T. terrenum arises without sacrificing the specificity for L-amino acids and α-ketoglutarate and in consensus with it.
Assuntos
Bactérias , Transaminases , Domínio Catalítico , Mutagênese Sítio-Dirigida , Especificidade por SubstratoRESUMO
Conformational plasticity of the functionally important regions and binding sites in protein/enzyme structures is one of the key factors affecting their function and interaction with substrates/ligands. Molecular dynamics (MD) can address the challenge of accounting for protein flexibility by predicting the time-dependent behavior of a molecular system. It has a potential of becoming a particularly important tool in protein engineering and drug discovery, but requires specialized training and skills, what impedes practical use by many investigators. We have developed the easyAmber - a comprehensive set of programs to automate the molecular dynamics routines implemented in the Amber package. The toolbox can address a wide set of tasks in computational biology struggling to account for protein flexibility. The automated workflow includes a complete set of steps from the initial "static" molecular model to the MD "production run": the full-atom model building, optimization/equilibration of the molecular system, classical/conventional and accelerated molecular dynamics simulations. The easyAmber implements advanced MD protocols, but is highly automated and easy-to-operate to attract a broad audience. The toolbox can be used on a personal desktop station equipped with a compatible gaming GPU-accelerator, as well as help to manage huge workloads on a powerful supercomputer. The software provides an opportunity to operate multiple simulations of different proteins at the same time, thus significantly increasing work efficiency. The easyAmber takes the molecular dynamics to the next level in terms of usability for complex processing of large volumes of data, thus supporting the recent trend away from inefficient "static" approaches in biology toward a deeper understanding of the dynamics in protein structures. The software is freely available for download at https://biokinet.belozersky.msu.ru/easyAmber, no login required.
Assuntos
Simulação de Dinâmica Molecular/estatística & dados numéricos , Conformação Proteica , Proteínas/química , Software , Algoritmos , Sítios de Ligação , Biologia Computacional , Descoberta de Drogas , Ligantes , Engenharia de ProteínasRESUMO
Doramapimod (BIRB-796) is widely recognized as one of the most potent and selective type II inhibitors of human p38α mitogen-activated protein kinase (MAPK); however, the understanding of its binding mechanism remains incomplete. Previous studies indicated high affinity of the ligand to a so-called allosteric pocket revealed only in the 'out' state of the DFG motif (i.e. Asp168-Phe169-Gly170) when Phe169 becomes fully exposed to the solvent. The possibility of alternative binding in the DFG-in state was hypothesized, but the molecular mechanism was not known. Methods of bioinformatics, docking and long-time scale classical and accelerated molecular dynamics have been applied to study the interaction of Doramapimod with the human p38α MAPK. It was shown that Doramapimod can bind to the protein even when the Phe169 is fully buried inside the allosteric pocket and the kinase activation loop is in the DFG-in state. Orientation of the inhibitor in such a complex is significantly different from that in the known crystallographic complex formed by the kinase in the DFG-out state; however, the Doramapimod's binding is followed by the ligand-induced conformational changes, which finally improve accommodation of the inhibitor. Molecular modelling has confirmed that Doramapimod combines the features of type I and II inhibitors of p38α MAPK, i.e. can directly and indirectly compete with the ATP binding. It can be concluded that optimization of the initial binding in the DFG-in state and the final accommodation in the DFG-out state should be both considered at designing novel efficient type II inhibitors of MAPK and homologous proteins. Communicated by Ramaswamy H. Sarma.
Assuntos
Aminoácidos/química , Proteína Quinase 14 Ativada por Mitógeno/química , Proteína Quinase 14 Ativada por Mitógeno/metabolismo , Naftalenos/farmacologia , Inibidores de Proteínas Quinases/farmacologia , Pirazóis/farmacologia , Regulação Alostérica/efeitos dos fármacos , Humanos , Proteína Quinase 14 Ativada por Mitógeno/antagonistas & inibidores , Simulação de Dinâmica MolecularRESUMO
The high catalytic efficiency of enzymes under reaction conditions is one of the main goals in biocatalysis. Despite the dramatic progress in the development of more efficient biocatalysts by protein design, the search for natural enzymes with useful properties remains a promising strategy. The pyridoxal 5'-phosphate (PLP)-dependent transaminases represent a group of industrially important enzymes due to their ability to stereoselectively transfer amino groups between diverse substrates; however, the complex mechanism of substrate recognition and conversion makes the design of transaminases a challenging task. Here we report a detailed structural and kinetic study of thermostable transaminase from the bacterium Thermobaculum terrenum (TaTT) using the methods of enzyme kinetics, X-ray crystallography and molecular modeling. TaTT can convert L-branched-chain and L-aromatic amino acids as well as (R)-(+)-1-phenylethylamine at a high rate and with high enantioselectivity. The structures of TaTT in complex with the cofactor pyridoxal 5'-phosphate covalently bound to enzyme and in complex with its reduced form, pyridoxamine 5'-phosphate, were determined at resolutions of 2.19 Å and 1.5 Å, and deposited in the Protein Data Bank as entries 6GKR and 6Q8E, respectively. TaTT is a fold type IV PLP-dependent enzyme. In terms of structural similarity, the enzyme is close to known branched-chain amino acid aminotransferases, but differences in characteristic sequence motifs in the active site were observed in TaTT compared to canonical branched-chain amino acid aminotransferases, which can explain the improved binding of aromatic amino acids and (R)-(+)-1-phenylethylamine. This study has shown for the first time that high substrate specificity towards both various l-amino acids and (R)-primary amines can be implemented within one pyridoxal 5'-phosphate-dependent active site of fold type IV. These results complement our knowledge of the catalytic diversity of transaminases and indicate the need for further biochemical and bioinformatic studies to understand the sequence-structure-function relationship in these enzymes.
Assuntos
Bactérias/enzimologia , Proteínas de Bactérias/química , Modelos Moleculares , Transaminases/química , Cristalografia por Raios X , Cinética , Domínios ProteicosRESUMO
Neuraminidase A (NanA) of the pathogen Streptococcus pneumoniae cleaves receptors of the human respiratory epithelial surface during bacterial colonization. The full-size structure of NanA that contains one lectin and one catalytic domain within a single polypeptide chain remains unresolved. Both domains are crucial for the microorganism's virulence and considered as promising antimicrobial targets. Methods of bioinformatics and molecular dynamics have been implemented to model NanA's structure and study interaction between the lectin and catalytic domains in three neuraminidases NanA, NanB, and NanC from Streptococcus pneumoniae. A significant difference in spatial organization of these homologous enzymes has been revealed. The lectin and catalytic domains of NanB and NanC form rigid globules stabilized by multiple interdomain interactions, whereas in NanA, the two domains are separated by a 16 amino acids long flexible linker - a characteristic of proteins that require conformational flexibility for their functioning. The biological role of this structural adaptation of NanA as a key virulence enzyme is discussed.
Assuntos
Proteínas de Bactérias/metabolismo , Lectinas/metabolismo , Neuraminidase/metabolismo , Streptococcus pneumoniae/enzimologia , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Biocatálise , Domínio Catalítico , Humanos , Isoenzimas/química , Isoenzimas/genética , Isoenzimas/metabolismo , Lectinas/química , Lectinas/genética , Simulação de Dinâmica Molecular , Neuraminidase/química , Neuraminidase/genética , Pneumonia Pneumocócica/microbiologia , Ligação Proteica , Streptococcus pneumoniae/genética , Streptococcus pneumoniae/patogenicidade , Virulência/genéticaRESUMO
Understanding the role of specific amino acid residues in the molecular mechanism of a protein's function is one of the most challenging problems in modern biology. A systematic bioinformatic analysis of protein families and superfamilies can help in the study of structure-function relationships and in the design of improved variants of enzymes/proteins, but represents a methodological challenge. The pyridoxal-5'-phosphate (PLP)-dependent enzymes are catalytically diverse and include the aspartate aminotransferase superfamily which implements a common structural framework known as type fold I. In this work, the recently developed bioinformatic online methods Mustguseal and Zebra were used to collect and study a large representative set of the aspartate aminotransferase superfamily with high structural, but low sequence similarity to l-threonine aldolase from Aeromonas jandaei (LTAaj), in order to identify conserved positions that provide general properties in the superfamily, and to reveal family-specific positions (FSPs) responsible for functional diversity. The roles of the identified residues in the catalytic mechanism and reaction specificity of LTAaj were then studied by experimental site-directed mutagenesis and molecular modelling. It was shown that FSPs determine reaction specificity by coordinating the PLP cofactor in the enzyme's active centre, thus influencing its activation and the tautomeric equilibrium of the intermediates, which can be used as hotspots to modulate the protein's functional properties. Mutagenesis at the selected FSPs in LTAaj led to a reduction in a native catalytic activity and increased the rate of promiscuous reactions. The results provide insight into the structural basis of catalytic promiscuity of the PLP-dependent enzymes and demonstrate the potential of bioinformatic analysis in studying structure-function relationship in protein superfamilies.
RESUMO
The visualCMAT web-server was designed to assist experimental research in the fields of protein/enzyme biochemistry, protein engineering, and drug discovery by providing an intuitive and easy-to-use interface to the analysis of correlated mutations/co-evolving residues. Sequence and structural information describing homologous proteins are used to predict correlated substitutions by the Mutual information-based CMAT approach, classify them into spatially close co-evolving pairs, which either form a direct physical contact or interact with the same ligand (e.g. a substrate or a crystallographic water molecule), and long-range correlations, annotate and rank binding sites on the protein surface by the presence of statistically significant co-evolving positions. The results of the visualCMAT are organized for a convenient visual analysis and can be downloaded to a local computer as a content-rich all-in-one PyMol session file with multiple layers of annotation corresponding to bioinformatic, statistical and structural analyses of the predicted co-evolution, or further studied online using the built-in interactive analysis tools. The online interactivity is implemented in HTML5 and therefore neither plugins nor Java are required. The visualCMAT web-server is integrated with the Mustguseal web-server capable of constructing large structure-guided sequence alignments of protein families and superfamilies using all available information about their structures and sequences in public databases. The visualCMAT web-server can be used to understand the relationship between structure and function in proteins, implemented at selecting hotspots and compensatory mutations for rational design and directed evolution experiments to produce novel enzymes with improved properties, and employed at studying the mechanism of selective ligand's binding and allosteric communication between topologically independent sites in protein structures. The web-server is freely available at https://biokinet.belozersky.msu.ru/visualcmat and there are no login requirements.