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(−)-Balanol is an adenosine triphosphate mimic that inhibits protein kinase C (PKC) isozymes and cAMP-dependent protein kinase (PKA) with limited selectivity. While PKA is known as a tumor promoter, PKC isozymes can be tumor promoters or suppressors. In particular, PKCε is frequently involved in tumorigenesis and a potential target for anticancer drugs. We recently reported that stereospecific fluorination of balanol yielded a balanoid with enhanced selectivity for PKCε over other PKC isozymes and PKA, although the global fluorine effect behind the selectivity enhancement is not fully understood. Interestingly, in contrast to PKA, PKCε is more sensitive to this fluorine effect. Here we investigate the global fluorine effect on the different binding responses of PKCε and PKA to balanoids using molecular dynamics (MD) simulations. For the first time to the best of our knowledge, we found that a structurally equivalent residue in each kinase, Thr184 in PKA and Ala549 in PKCε, is essential for the different binding responses. Furthermore, the study revealed that the invariant Lys, Lys73 in PKA and Lys437 in PKCε, already known to have a crucial role in the catalytic activity of kinases, serves as the main anchor for balanol binding. Overall, while Thr184 in PKA attenuates the effect of fluorination, Ala549 permits remote response of PKCε to fluorine substitution, with implications for rational design of future balanol-based PKCε inhibitors.

Olfactory receptor (OR) 1A2 is the member of largest superfamily of G protein-coupled receptors (GPCRs). OR1A2 is an ectopically expressed receptor with only 13 known ligands, implicated in reducing hepatocellular carcinoma progression, with enormous therapeutic potential. We have developed a two-stage screening approach to identify novel putative ligands of OR1A2. We first used a pharmacophore model based on atomic property field (APF) to virtually screen a library of 5942 human metabolites. We then carried out structure-based virtual screening (SBVS) for predicting the potential agonists, based on a 3D homology model of OR1A2. This model was developed using a biophysical approach for template selection, based on multiple parameters including hydrophobicity correspondence, applied to the complete set of available GPCR structures to pick the most appropriate template. Finally, the membrane-embedded 3D model was refined by molecular dynamics (MD) simulations in both the apoand holoforms. The refined model in the apoform was selected for SBVS. Four novel small molecules were identified as strong binders to this olfactory receptor on the basis of computed binding energies.

The evidence that any protein exists in the Human Proteome Project (HPP; protein evidence 1 or PE1) has revolved primarily (although not exclusively) around mass spectrometry (MS) (93% of PE1 proteins have MS evidence in the latest neXtProt release), with robust and stringent, well-curated metrics that have served the community well. This has led to a significant number of proteins still considered “missing” (i.e., PE2–4). Many PE2–4 proteins have MS evidence of unacceptable quality (small or not enough unitypic peptides and unacceptably high protein/peptide FDRs), transcriptomic, or antibody evidence. Here we use a Chromosome 7 PE2 example called Prestinto demonstrate that clear and robust criteria/metrics need to be developed for proteins that may not or cannot produce clear-cut MS evidence while possessing significant non-MS evidence, including disease-association data. Many of the PE2–4 proteins are inaccessible, spatiotemporally expressed in a limited way, or expressed at such a very low copy number as to be unable to be detected by current MS methodologies. We propose that the HPP community consider and lead a communal initiative to accelerate the discovery and characterization of these types of “missing” proteins.

Claudins are the major transmembrane protein components of tight junctions in human endothelia and epithelia. Tissue-specific expression of claudin members suggests that this protein family is not only essential for sustaining the role of tight junctions in cell permeability control but also vital in organizing cell contact signaling by protein–protein interactions. How this protein family is collectively processed and regulated is key to understanding the role of junctional proteins in preserving cell identity and tissue integrity. The focus of this review is to first provide a brief overview of the functional context, on the basis of the extensive body of claudin biology research that has been thoroughly reviewed, for endogenous human claudin members and then ascertain existing and future proteomics techniques that may be applicable to systematically characterizing the chemical forms and interacting protein partners of this protein family in human. The ability to elucidate claudin-based signaling networks may provide new insight into cell development and differentiation programs that are crucial to tissue stability and manipulation.

This paper summarizes the recent activities of the Chromosome-Centric Human Proteome Project (C-HPP) consortium, which develops new technologies to identify yet-to-be annotated proteins (termed “missing proteins”) in biological samples that lack sufficient experimental evidence at the protein level for confident protein identification. The C-HPP also aims to identify new protein forms that may be caused by genetic variability, post-translational modifications, and alternative splicing. Proteogenomic data integration forms the basis of the C-HPP’s activities; therefore, we have summarized some of the key approaches and their roles in the project. We present new analytical technologies that improve the chemical space and lower detection limits coupled to bioinformatics tools and some publicly available resources that can be used to improve data analysis or support the development of analytical assays. Most of this paper’s content has been compiled from posters, slides, and discussions presented in the series of C-HPP workshops held during 2014. All data (posters, presentations) used are available at the C-HPP Wiki (http://c-hpp.webhosting.rug.nl/) and in the Supporting Information.

Urokinase plasminogen activator receptor (uPAR) and the epithelial integrin αvβ6 are thought to individually play critical roles in cancer metastasis. These observations have been highlighted by the recent discovery (by proteomics) of an interaction between these two molecules, which are also both implicated in the epithelial–mesenchymal transition (EMT) that facilitates escape of cells from tissue barriers and is a common signature of cancer metastases. In this study, orthogonal in cellulo and in vitro functional proteomic approaches were used to better characterize the uPAR·αvβ6 interaction. Proximity ligation assays (PLA) confirmed the uPAR·αvβ6 interaction on OVCA429 (ovarian cancer line) and four different colon cancer cell lines including positive controls in cells with de novo β6 subunit expression. PLA studies were then validated using peptide arrays, which also identified potential physical sites of uPAR interaction with αvβ6, as well as verifying interactions with other known uPAR ligands (e.g., uPA, vitronectin) and individual integrin subunits (i.e., αv, β1, β3, and β6 alone). Our data suggest that interaction with uPAR requires expression of the complete αβ heterodimer (e.g., αvβ6), not individual subunits (i.e., αv, β1, β3, or β6). Finally, using in silico structural analyses in concert with these functional proteomics studies, we propose and demonstrate that the most likely unique sites of interaction between αvβ6 and uPAR are located in uPAR domains II and III.

Molecular function in cellular processes is governed by protein-protein interactions (PPIs) within biological networks. Selective yet specific association of these protein partners contributes to diverse functionality such as catalysis, regulation, assembly, immunity, and inhibition in a cell. Therefore, understanding the principles of protein-protein association has been of immense interest for several decades. We provide an overview of the experimental methods used to determine PPIs and the key databases archiving this information. Structural and functional information of existing protein complexes confers knowledge on the principles of PPI, based on which a classification scheme for PPIs is then introduced. Obtaining high-quality non-redundant datasets of protein complexes for interaction characterisation is an essential step towards deciphering their underlying binding principles. Analysis of physicochemical features and their documentation has enhanced our understanding of the molecular basis of protein-protein association. We describe the diverse datasets created/collected by various groups and their key findings inferring distinguishing features. The currently available interface databases and prediction servers have also been compiled.

The chromosome-centric human proteome project (C-HPP) aims to define the complete set of proteins encoded in each human chromosome. The neXtProt database (September 2013) lists 20 128 proteins for the human proteome, of which 3831 human proteins (∼19%) are considered “missing” according to the standard metrics table (released September 27, 2013). In support of the C-HPP initiative, we have extended the annotation strategy developed for human chromosome 7 “missing” proteins into a semiautomated pipeline to functionally annotate the “missing” human proteome. This pipeline integrates a suite of bioinformatics analysis and annotation software tools to identify homologues and map putative functional signatures, gene ontology, and biochemical pathways. From sequential BLAST searches, we have primarily identified homologues from reviewed nonhuman mammalian proteins with protein evidence for 1271 (33.2%) “missing” proteins, followed by 703 (18.4%) homologues from reviewed nonhuman mammalian proteins and subsequently 564 (14.7%) homologues from reviewed human proteins. Functional annotations for 1945 (50.8%) “missing” proteins were also determined. To accelerate the identification of “missing” proteins from proteomics studies, we generated proteotypic peptides in silico. Matching these proteotypic peptides to ENCODE proteogenomic data resulted in proteomic evidence for 107 (2.8%) of the 3831 “missing proteins, while evidence from a recent membrane proteomic study supported the existence for another 15 “missing” proteins. The chromosome-wise functional annotation of all “missing” proteins is freely available to the scientific community through our web server (http://biolinfo.org/protannotator).

The black Périgord truffle (Tuber melanosporumVittad.) is a highly prized food today, with its unique scent (i.e., perfume) and texture. Despite these attributes, it remains relatively poorly studied, lacking “omics” information to characterize its biology and biochemistry, especially changes associated with freshness and the proteins/metabolites responsible for its organoleptic properties. In this study, we have functionally annotated the truffle proteome from the 2010 T. melanosporumgenome comprising 12 771 putative nonredundant proteins. Using sequential BLAST search strategies, we identified homologues for 2587 proteins with 2486 (96.0%) fungal homologues (available from http://biolinfo.org/protannotator/blacktruffle.php). A combined 1D PAGE and high-accuracy LC–MS/MS proteomic study was employed to validate the results of the functional annotation and identified 836 (6.5%) proteins, of which 47.5% (i.e., 397) were present in our bioinformatics studies. Our study, functionally annotating 6487 black Périgord truffle proteins and confirming 836 by proteomic experiments, is by far the most comprehensive study to date contributing significantly to the scientific community. This study has resulted in the functional characterization of novel proteins to increase our biological understanding of this organism and to uncover potential biomarkers of authenticity, freshness, and perfume maturation.

The chromosome-centric human proteome project aims to systematically map all human proteins, chromosome by chromosome, in a gene-centric manner through dedicated efforts from national and international teams. This mapping will lead to a knowledge-based resource defining the full set of proteins encoded in each chromosome and laying the foundation for the development of a standardized approach to analyze the massive proteomic data sets currently being generated. The neXtProt database lists 946 proteins as the human proteome of chromosome 7. However, 170 (18%) proteins of human chromosome 7 have no evidence at the proteomic, antibody, or structural levels and are considered “missing” in this study as they lack experimental support. We have developed a protocol for the functional annotation of these “missing” proteins by integrating several bioinformatics analysis and annotation tools, sequential BLAST homology searches, protein domain/motif and gene ontology (GO) mapping, and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. Using the BLAST search strategy, homologues for reviewed non-human mammalian proteins with protein evidence were identified for 90 “missing” proteins while another 38 had reviewed non-human mammalian homologues. Putative functional annotations were assigned to 27 of the remaining 43 novel proteins. Proteotypic peptides have been computationally generated to facilitate rapid identification of these proteins. Four of the “missing” chromosome 7 proteins have been substantiated by the ENCODE proteogenomic peptide data.

Combinatorial synthesis and high‐throughput screening (HTS) are playing increasingly important roles in chemoinformatics. This review gives an overview of the strategies available for library design and compound selection. Although the traditional approach of diversity‐oriented library design continues to be an important criterion in lead generation, nevertheless, pharmacokinetic properties are also widely recognized in compound selection for generating lead libraries. We summarize all the current molecular similarity and diversity methods employed in chemoinformatics to design lead libraries for in silicodrug discovery. We have also included a section on popular molecular descriptors and similarity/diversity coefficients. Recent developments, include multi‐optimization design algorithms to select suitable molecules, such as Pareto‐optimization, representing a compromise between several competing objectives, have also been discussed in the context of virtual screening and library design. Drug Dev Res 72: 74–84, 2011. © 2010 Wiley‐Liss, Inc.

To infect their mammalian hosts, Fasciola hepatica larvae must penetrate and traverse the intestinal wall of the duodenum, move through the peritoneum, and penetrate the liver. After migrating through and feeding on the liver, causing extensive tissue damage, the parasites move to their final niche in the bile ducts where they mature and produce eggs. Here we integrated a transcriptomics and proteomics approach to profile Fasciola secretory proteins that are involved in host-pathogen interactions and to correlate changes in their expression with the migration of the parasite. Prediction of F. hepatica secretory proteins from 14,031 expressed sequence tags (ESTs) available from the Wellcome Trust Sanger Centre using the semiautomated EST2Secretome pipeline showed that the major components of adult parasite secretions are proteolytic enzymes including cathepsin L, cathepsin B, and asparaginyl endopeptidase cysteine proteases as well as novel trypsin-like serine proteases and carboxypeptidases. Proteomics analysis of proteins secreted by infective larvae, immature flukes, and adult F. hepatica showed that these proteases are developmentally regulated and correlate with the passage of the parasite through host tissues and its encounters with different host macromolecules. Proteases such as FhCL3 and cathepsin B have specific functions in larvae activation and intestinal wall penetration, whereas FhCL1, FhCL2, and FhCL5 are required for liver penetration and tissue and blood feeding. Besides proteases, the parasites secrete an array of antioxidants that are also highly regulated according to their migration through host tissues. However, whereas the proteases of F. hepatica are secreted into the parasite gut via a classical endoplasmic reticulum/Golgi pathway, we speculate that the antioxidants, which all lack a signal sequence, are released via a non-classical trans-tegumental pathway.

To infect their mammalian hosts, Fasciola hepaticalarvae must penetrate and traverse the intestinal wall of the duodenum, move through the peritoneum, and penetrate the liver. After migrating through and feeding on the liver, causing extensive tissue damage, the parasites move to their final niche in the bile ducts where they mature and produce eggs. Here we integrated a transcriptomics and proteomics approach to profile Fasciolasecretory proteins that are involved in host-pathogen interactions and to correlate changes in their expression with the migration of the parasite. Prediction of F. hepaticasecretory proteins from 14,031 expressed sequence tags (ESTs) available from the Wellcome Trust Sanger Centre using the semiautomated EST2Secretome pipeline showed that the major components of adult parasite secretions are proteolytic enzymes including cathepsin L, cathepsin B, and asparaginyl endopeptidase cysteine proteases as well as novel trypsin-like serine proteases and carboxypeptidases. Proteomics analysis of proteins secreted by infective larvae, immature flukes, and adult F. hepaticashowed that these proteases are developmentally regulated and correlate with the passage of the parasite through host tissues and its encounters with different host macromolecules. Proteases such as FhCL3 and cathepsin B have specific functions in larvae activation and intestinal wall penetration, whereas FhCL1, FhCL2, and FhCL5 are required for liver penetration and tissue and blood feeding. Besides proteases, the parasites secrete an array of antioxidants that are also highly regulated according to their migration through host tissues. However, whereas the proteases of F. hepaticaare secreted into the parasite gut via a classical endoplasmic reticulum/Golgi pathway, we speculate that the antioxidants, which all lack a signal sequence, are released via a non-classical trans-tegumental pathway.

abstractIn order to promote the awareness of bioinformatics, the availability of computational and database resources and the advancement of bioinformatics research competency in the Asia Pacific region, the National University of Singapore (NUS), Asia Pacific Bioinformatics Network (APBioNet), S* Life Science Informatics Alliance and Sun Microsystems’ Asia Pacific Science and Technology Center (APSTC) are collaborating to develop various components leading to a bioinformatics educational grid. Freely accessible via the Internet, this education grid combines (a) educational material from the S* Alliance, including audio-video teaching material from Singapore, Stanford, Sweden (Karolinska Institutet and Uppsala University), University of Sydney, University of California San Diego, South African National Bioinformatics Institute (SANBI) and Macquarie University Sydney, (b) problem-based learning and tutorial modules from S* Alliance, (c) APBioBox software from APBioNet funded by IDRC Pan Asia Networking project, (d) Bio-Cluster Grid software from Sun Microsystems, (e) biological databases from the Bio-Mirrors project of APBioNet and the Asia Pacific Advanced Network (APAN), and (f) audio-conferencing emeeting system and the IVLE system from Centre for Instructional Technology, National University of Singapore. Strategies on building this educational grid with leading agencies in the region are also discussed.

The S‐Star Trial Bioinformatics on‐line course () is a global experiment in bioinformatics distance education. Six universities from five continents have participated in this project. One hundred and fifty students participated in the first trial course of which 96 followed through the entire course and 70 fulfilled the overall course requirements. The course was built up of 12 lectures covering different basic and advanced topics within bioinformatics. The lectures consist of streaming video and synchronized slides with follow‐up discussion forums and a final assessment. It draws on experts from diverse institutions to share their teaching expertise and resources via distance learning. A major goal of S‐Star is to provide free introductory web‐based education. Here we present the outline of the course, experiences from a global collaboration, and feedback from the first trial of the on‐line S‐Star course.

An important and exciting challenge in the postgenomic era is to understand the functions of newly discovered proteins based on their structures. The main thrust is to find the common structural motifs that contribute to specific functions. Using this premise, here we report the purification, solution NMR, and functional characterization of a novel class of weak potassium channel toxins from the venom of the scorpion Heterometrus fulvipes. These toxins, κ-hefutoxin1 and κ-hefutoxin2, exhibit no homology to any known toxins. NMR studies indicate that κ-hefutoxin1 adopts a unique three-dimensional fold of two parallel helices linked by two disulfide bridges without any β−sheets. Based on the presence of the functional diad (Tyr5/Lys19) at a distance (6.0 ± 1.0 Å) comparable with other potassium channel toxins, we hypothesized its function as a potassium channel toxin. κ-Hefutoxin 1 not only blocks the voltage-gated K+-channels, Kv1.3 and Kv1.2, but also slows the activation kinetics of Kv1.3 currents, a novel feature of κ-hefutoxin 1, unlike other scorpion toxins, which are considered solely pore blockers. Alanine mutants (Y5A, K19A, and Y5A/K19A) failed to block the channels, indicating the importance of the functional diad.

Secretion of whey acidic protein (WAP) in milk throughout lactation has previously been reported for a limited number of species, including the mouse, rat, rabbit, camel, and pig. We report here the isolation of WAP from the milk of a marsupial, the tammar wallaby (Macropus eugenii). Tammar WAP (tWAP) was isolated by reverse-phase HPLC and migrates in SDS-polyacrylamide gel electrophoresis at 29.9 kDa. tWAP is the major whey protein, but in contrast to eutherians, secretion is asynchronous and occurs only from approximately days 130 through 240 of lactation. The full-length cDNA codes for a mature protein of 191 amino acids, which is comprised of three four-disulfide core domains, contrasting with the two four-disulfide core domain arrangement in all other known WAPs. A three-dimensional model for tWAP has been constructed and suggests that the three domains have little interaction and could function independently. Analysis of the amino acid sequence suggests the protein belongs to a family of protease inhibitors; however, the predicted active site of these domains is dissimilar to the confirmed active site for known protease inhibitors. This suggests that any putative protease ligand may be unique to either the mammary gland, milk, or gut of the pouch young. Examination of the endocrine regulation of the tWAPgene showed consistently that the gene is prolactin-responsive but that the endocrine requirements for induction and maintenance of tWAPgene expression are different during lactation.

In humans, mutations in SOX9result in a skeletal malformation syndrome, campomelic dysplasia (CD). The present study investigated two major classes of CD mutations: 1) point mutations in the high mobility group (HMG) domain and 2) truncations and frameshifts that alter the C terminus of the protein. We analyzed the effect of one novel mutation and three other point mutations in the HMG domain of SOX9 on the DNA binding and DNA bending properties of the protein. The F12L mutant HMG domain shows negligible DNA binding, the H65Y mutant shows minimal DNA binding, whereas the A19V mutant shows near wild type DNA binding and bends DNA normally. Interestingly, the P70R mutant has altered DNA binding specificity, but also bends DNA normally. The effects of the point mutations were interpreted using a molecular model of the SOX9 HMG domain. We analyzed the effects upon transcription of mutations resembling the truncation and frameshift mutations in CD patients, and found that progressive deletion of the C terminus causes progressive loss of transactivation. Maximal transactivation by SOX9 requires both the C-terminal domain rich in proline, glutamine, and serine and the adjacent domain composed entirely of proline, glutamine, and alanine. Thus, CD arises by mutations that interfere with DNA binding by SOX9 or truncate the C-terminal transactivation domain and thereby impede the ability of SOX9 to activate target genes during organ development.

Energy profileGramicidin AEthanolamine endCaesiumPotassiumSodiumEnergy barrierTheoretical computation

Abstract: Thecndo/Force method has been employed in the determination of quadratic potential functions for the complexes of lithium cation with formaldehyde and formamide. The O, Li+ stretching frequency and the COLi+ bending frequencies have been estimated after scaling, the stretching and stretch-stretch elements of the force constant matrix. The transferability of the donor potential function to the complex has been verified.

The energy profiles for single occupancy by Cs +and Na +in the gramicidin A channel assumed to be in a head-to-head β6.33.3helical dimeric structure, were computed: (A) allowing complete conformational freedom to the ethanolamine end, (B) constraining it to stay in its intrinsically preferred conformation. Whatever the constraint, both the entrance barrier and the central barrier appear in the order Cs +< K +< Na +. Introducing the flexibility of the tail modifies appreciably the profiles and the location of the extrema along it.

Thecndo/Force method has been employed in the determination of quadratic potential functions for the complexes of lithium cation with formaldehyde and formamide. The O, Li+stretching frequency and the COLi+bending frequencies have been estimated after scaling, the stretching and stretch-stretch elements of the force constant matrix. The transferability of the donor potential function to the complex has been verified.

The iSwathX web application processes and normalizes mass spectrometry−based proteomics spectral libraries generated in the data‐dependent acquisition (DDA) approach. These libraries are stored in various proteomics repositories such as PeptideAtlas and NIST, or are user‐generated and provide reference data for data‐independent acquisition (DIA) targeted data extraction and analysis. iSwathX 2.0 can efficiently normalize DDA data from different instruments, gathered at different instances, and make it compatible with specific DIA experiments. Novel functions for parallel processing of DDA libraries and DIA report files, along with various data visualizations, are available in iSwathX 2.0. The step‐by‐step protocols provided here describe how the libraries are uploaded, processed, visualized, and downloaded using various modules of the application. They also provide detailed guidelines on the use of DIA report files for data analysis and visualization. © 2020 Wiley Periodicals LLC. Basic Protocol 1: Processing, combining, and visualizing two DDA libraries Basic Protocol 2: Parallel processing and combination of multiple DDA libraries Basic Protocol 3: Downstream processing, comparison, and visualization of DIA report files

Binding of short antigenic peptides to Major histocompatibility complex (MHC) proteins is the first step in T-cell mediated immune response. To understand the structural principles governing MHC-specific peptide recognition and binding, we have developed the MHC-Peptide Interaction Database (MPID), containing sequence-structure-function information. MPID (version 1.2) contains curated x-ray crystallographic data on 86 MHC peptide complexes, with precomputed interaction parameters (solvent accessibility, hydrogen bonds, gap volume and gap index). A user-friendly web interface and query tools will facilitate the development of predictive algorithms for MHC-peptide binding from a structural viewpoint.

The relationship between intron distribution in the eukaryotic gene and protein structural elements is essential for understanding the origin and evolution of genes. XdomView is a web-based viewer mapping protein structural domains and intron positions in eukaryotic homologues to its tertiary structure. The association of sequence signals to 3D structure in XdomView provides a valuable visualization environment for eukaryotic gene organization, gene evolution, protein folding and protein structure classification.

Motivation: While processing of MHC class II antigens for presentation to helper T-cells is essential for normal immune response, it is also implicated in the pathogenesis of autoimmune disorders and hypersensitivity reactions. Sequence-based computational techniques for predicting HLA-DQ binding peptides have encountered limited success, with few prediction techniques developed using three-dimensional models. Methods: We describe a structure-based prediction model for modeling peptide-DQ3.2β complexes. We have developed a rapid and accurate protocol for docking candidate peptides into the DQ3.2β receptor and a scoring function to discriminate binders from the background. The scoring function was rigorously trained, tested and validated using experimentally verified DQ3.2β binding and non-binding peptides obtained from biochemical and functional studies. Results: Our model predicts DQ3.2β binding peptides with high accuracy [area under the receiver operating characteristic (ROC) curve AROC > 0.90], compared with experimental data. We investigated the binding patterns of DQ3.2β peptides and illustrate that several registers exist within a candidate binding peptide. Further analysis reveals that peptides with multiple registers occur predominantly for high-affinity binders. Contact: shoba@els.mq.edu.au Supplementary information: Supplementary data is available at Bioinformatics online.