Targeting the YXXΦ Motifs of the SARS Coronaviruses 1 and 2 ORF3a Peptides by In Silico Analysis to Predict Novel Virus-Host Interactions

The emerging SARS-CoV and SARS-CoV-2 belong to the family of "common cold" RNA coronaviruses, and they are responsible for the 2003 epidemic and the current pandemic with over 6.3 M deaths worldwide. The ORF3a gene is conserved in both viruses and codes for the accessory protein ORF3a, with unclear functions, possibly related to viral virulence and pathogenesis. The tyrosine-based YXXΦ motif (Φ: bulky hydrophobic residue-L/I/M/V/F) was originally discovered to mediate clathrin-dependent endocytosis of membrane-spanning proteins. Many viruses employ the YXXΦ motif to achieve efficient receptor-guided internalisation in host cells, maintain the structural integrity of their capsids and enhance viral replication. Importantly, this motif has been recently identified on the ORF3a proteins of SARS-CoV and SARS-CoV-2. Given that the ORF3a aa sequence is not fully conserved between the two SARS viruses, we aimed to map in silico structural differences and putative sequence-driven alterations of regulatory elements within and adjacently to the YXXΦ motifs that could predict variations in ORF3a functions. Using robust bioinformatics tools, we investigated the presence of relevant post-translational modifications and the YXXΦ motif involvement in protein-protein interactions. Our study suggests that the predicted YXXΦ-related features may confer specific-yet to be discovered-functions to ORF3a proteins, significant to the new virus and related to enhanced propagation, host immune regulation and virulence.

Comprehensive identification of protein orthologs in the family Ascoviridae facilitates an understanding of phylogenomics, protein conservation, and phosphorylation

Analysis of orthology is important for understanding protein conservation, function, and phylogenomics. In this study, we performed a comprehensive analysis of gene orthology in the family Ascoviridae based on identification of 366 protein homologue groups and phylogenetic analysis of 34 non-single-copy proteins. Our findings revealed 90 newly annotated proteins, five newly identified core proteins for the family Ascoviridae, and 14 core proteins for the genus Ascovirus. A phylogenomic tree of 11 Ascoviridae members was constructed based on a concatenation of 35 of the 45 ortholog groups. In combination with phosphoproteomic results and conservation estimations, 30 conserved phosphorylation sites on 17 phosphoproteins were identified from a total of 176 phosphosites on 57 phosphoproteins from Heliothis virescens ascovirus 3h (HvAV-3h), providing potential research targets for investigating the role of these protein in the regulation of viral infection. This study will facilitate genome annotation and comparison of further Ascoviridae members as well as functional genomic investigations.

VPTMdb: a viral posttranslational modification database

In viruses, posttranslational modifications (PTMs) are essential for their life cycle. Recognizing viral PTMs is very important for a better understanding of the mechanism of viral infections and finding potential drug targets. However, few studies have investigated the roles of viral PTMs in virus-human interactions using comprehensive viral PTM datasets. To fill this gap, we developed the first comprehensive viral posttranslational modification database (VPTMdb) for collecting systematic information of PTMs in human viruses and infected host cells. The VPTMdb contains 1240 unique viral PTM sites with 8 modification types from 43 viruses (818 experimentally verified PTM sites manually extracted from 150 publications and 422 PTMs extracted from SwissProt) as well as 13 650 infected cells' PTMs extracted from seven global proteomics experiments in six human viruses. The investigation of viral PTM sequences motifs showed that most viral PTMs have the consensus motifs with human proteins in phosphorylation and five cellular kinase families phosphorylate more than 10 viral species. The analysis of protein disordered regions presented that more than 50% glycosylation sites of double-strand DNA viruses are in the disordered regions, whereas single-strand RNA and retroviruses prefer ordered regions. Domain-domain interaction analysis indicating potential roles of viral PTMs play in infections. The findings should make an important contribution to the field of virus-human interaction. Moreover, we created a novel sequence-based classifier named VPTMpre to help users predict viral protein phosphorylation sites. VPTMdb online web server (http://vptmdb.com:8787/VPTMdb/) was implemented for users to download viral PTM data and predict phosphorylation sites of interest.

Phosphorylation Time-Course Study of the Response during Adenovirus Type 2 Infection

PTMs such as phosphorylations are usually involved in signal transduction pathways. To investigate the temporal dynamics of phosphoproteome changes upon viral infection, a model system of IMR-90 cells infected with human adenovirus type 2 (Ad2) is used in a time-course quantitative analysis combining titanium dioxide (TiO₂ ) particle enrichment and SILAC-MS. Quantitative data from 1552 phosphorylated sites clustered the highly altered phosphorylated sites to the signaling by rho family GTPases, the actin cytoskeleton signaling, and the cAMP-dependent protein kinase A signaling pathways. Their activation is especially pronounced at early time post-infection. Changes of several phosphorylated sites involved in the glycolysis pathway, related to the activation of the Warburg effect, point at virus-induced energy production. For Ad2 proteins, 32 novel phosphorylation sites are identified and as many as 52 phosphorylated sites on 17 different Ad2 proteins are quantified, most of them at late time post-infection. Kinase predictions highlighted activation of PKA, CDK1/2, MAPK, and CKII. Overlaps of kinase motif sequences for viral and human proteins are observed, stressing the importance of phosphorylation during Ad2 infection.

The Potential Role of the ZIKV NS5 Nuclear Spherical-Shell Structures in Cell Type-Specific Host Immune Modulation during ZIKV Infection

The Zika virus (ZIKV) non-structural protein 5 (NS5) plays multiple viral and cellular roles during infection, with its primary role in virus RNA replication taking place in the cytoplasm. However, immunofluorescence assay studies have detected the presence of ZIKV NS5 in unique spherical shell-like structures in the nuclei of infected cells, suggesting potentially important cellular roles of ZIKV NS5 in the nucleus. Hence ZIKV NS5′s subcellular distribution and localization must be tightly regulated during ZIKV infection. Both ZIKV NS5 expression or ZIKV infection antagonizes type I interferon signaling, and induces a pro-inflammatory transcriptional response in a cell type-specific manner, but the mechanisms involved and the role of nuclear ZIKV NS5 in these cellular functions has not been elucidated. Intriguingly, these cells originate from the brain and placenta, which are also organs that exhibit a pro-inflammatory signature and are known sites of pathogenesis during ZIKV infection in animal models and humans. Here, we discuss the regulation of the subcellular localization of the ZIKV NS5 protein, and its putative role in the induction of an inflammatory response and the occurrence of pathology in specific organs during ZIKV infection.

PIM kinases facilitate lentiviral evasion from SAMHD1 restriction via Vpx phosphorylation

Lentiviruses have evolved to acquire an auxiliary protein Vpx to counteract the intrinsic host restriction factor SAMHD1. Although Vpx is phosphorylated, it remains unclear whether such phosphorylation indeed regulates its activity toward SAMHD1. Here we identify the PIM family of serine/threonine protein kinases as the factors responsible for the phosphorylation of Vpx and the promotion of Vpx-mediated SAMHD1 counteraction. Integrated proteomics and subsequent functional analysis reveal that PIM family kinases, PIM1 and PIM3, phosphorylate HIV-2 Vpx at Ser13 and stabilize the interaction of Vpx with SAMHD1 thereby promoting ubiquitin-mediated proteolysis of SAMHD1. Inhibition of the PIM kinases promotes the antiviral activity of SAMHD1, ultimately reducing viral replication. Our results highlight a new mode of virus–host cell interaction in which host PIM kinases facilitate promotion of viral infectivity by counteracting the host antiviral system, and suggest a novel therapeutic strategy involving restoration of SAMHD1-mediated antiviral response.

The accessory lentiviral protein X (Vpx) of the SIV_smm/mac and HIV-2 lineage targets the host-restriction factor SAMHD1 for proteasomal degradation. Here, the authors show that host PIM kinase-mediated phosphorylation of Vpx stabilizes its interaction with SAMHD1, suggesting PIM as potential antiviral targets.

Host-Driven Phosphorylation Appears to Regulate the Budding Activity of the Lassa Virus Matrix Protein

Lassa mammarenavirus (LASV) is an enveloped RNA virus that can cause Lassa fever, an acute hemorrhagic fever syndrome associated with significant morbidity and high rates of fatality in endemic regions of western Africa. The arenavirus matrix protein Z has several functions during the virus life cycle, including coordinating viral assembly, driving the release of new virus particles, regulating viral polymerase activity, and antagonizing the host antiviral response. There is limited knowledge regarding how the various functions of Z are regulated. To investigate possible means of regulation, mass spectrometry was used to identify potential sites of phosphorylation in the LASV Z protein. This analysis revealed that two serines (S18, S98) and one tyrosine (Y97) are phosphorylated in the flexible N- and C-terminal regions of the protein. Notably, two of these sites, Y97 and S98, are located in (Y97) or directly adjacent to (S98) the PPXY late domain, an important motif for virus release. Studies with non-phosphorylatable and phosphomimetic Z proteins revealed that these sites are important regulators of the release of LASV particles and that host-driven, reversible phosphorylation may play an important role in the regulation of LASV Z protein function.

Temporal characterization of the non-structural Adenovirus type 2 proteome and phosphoproteome using high-resolving mass spectrometry

The proteome and phosphoproteome of non-structural proteins of Adenovirus type 2 (Ad2) were time resolved using a developed mass spectrometry approach. These proteins are expressed by the viral genome and important for the infection process, but not part of the virus particle. We unambiguously confirm the existence of 95% of the viral proteins predicted to be encoded by the viral genome. Most non-structural proteins peaked in expression at late time post infection. We identified 27 non-redundant sites of phosphorylation on seven different non-structural proteins. The most heavily phosphorylated protein was the DNA binding protein (DBP) with 15 different sites. The phosphorylation occupancy rate could be calculated and monitored with time post infection for 15 phosphorylated sites on various proteins. In the DBP, phosphorylations with time-dependent relation were observed. The findings show the complexity of the Ad2 non-structural proteins and opens up a discussion for potential new drug targets.

Overlapping Regions in HIV-1 Genome Act as Potential Sites for Host-Virus Interaction

More than a decade, overlapping genes in RNA viruses became a subject of research which has explored various effect of gene overlapping on the evolution and function of viral genomes like genome size compaction. Additionally, overlapping regions (OVRs) are also reported to encode elevated degree of protein intrinsic disorder (PID) in unspliced RNA viruses. With the aim to explore the roles of OVRs in HIV-1 pathogenesis, we have carried out an in-depth analysis on the association of gene overlapping with PID in 35 HIV1- M subtypes. Our study reveals an over representation of PID in OVR of HIV-1 genomes. These disordered residues endure several vital, structural features like short linear motifs (SLiMs) and protein phosphorylation (PP) sites which are previously shown to be involved in massive host–virus interaction. Moreover, SLiMs in OVRs are noticed to be more functionally potential as compared to that of non-overlapping region. Although, density of experimentally verified SLiMs, resided in 9 HIV-1 genes, involved in host–virus interaction do not show any bias toward clustering into OVR, tat and rev two important proteins mediates host–pathogen interaction by their experimentally verified SLiMs, which are mostly localized in OVR. Finally, our analysis suggests that the acquisition of SLiMs in OVR is mutually exclusive of the occurrence of disordered residues, while the enrichment of PPs in OVR is solely dependent on PID and not on overlapping coding frames. Thus, OVRs of HIV-1 genomes could be demarcated as potential molecular recognition sites during host–virus interaction.

The C-terminal 18 Amino Acid Region of Dengue Virus NS5 Regulates its Subcellular Localization and Contains a Conserved Arginine Residue Essential for Infectious Virus Production

Dengue virus NS5 is the most highly conserved amongst the viral non-structural proteins and is responsible for capping, methylation and replication of the flavivirus RNA genome. Interactions of NS5 with host proteins also modulate host immune responses. Although replication occurs in the cytoplasm, an unusual characteristic of DENV2 NS5 is that it localizes to the nucleus during infection with no clear role in replication or pathogenesis. We examined NS5 of DENV1 and 2, which exhibit the most prominent difference in nuclear localization, employing a combination of functional and structural analyses. Extensive gene swapping between DENV1 and 2 NS5 identified that the C-terminal 18 residues (Cter₁₈) alone was sufficient to direct the protein to the cytoplasm or nucleus, respectively. The low micromolar binding affinity between NS5 Cter₁₈ and the nuclear import receptor importin-alpha (Impα), allowed their molecular complex to be purified, crystallised and visualized at 2.2 Å resolution using x-ray crystallography. Structure-guided mutational analysis of this region in GFP-NS5 clones of DENV1 or 2 and in a DENV2 infectious clone reveal residues important for NS5 subcellular localization. Notably, the trans conformation adopted by Pro-884 allows proper presentation for binding Impα and mutating this proline to Thr, as present in DENV1 NS5, results in mislocalizaion of NS5 to the cytoplasm without compromising virus fitness. In contrast, a single mutation to alanine at NS5 position R888, a residue conserved in all flaviviruses, resulted in a completely non-viable virus, and the R888K mutation led to a severely attenuated phentoype, even though NS5 was located in the nucleus. R888 forms a hydrogen bond with Y838 that is also conserved in all flaviviruses. Our data suggests an evolutionarily conserved function for NS5 Cter₁₈, possibly in RNA interactions that are critical for replication, that is independent of its role in subcellular localization.

DENV NS5 is critical for virus RNA replication and an important drug target based on its high sequence conservation across serotypes, and the successful development of potent drugs that target the homologous NS5B of hepatitis C virus. NS5 also mediates other functions that are important for innate and adaptive immune responses by the infected host. Extensive gene swapping and functional analyses between NS5 of DENV serotypes 1 and 2, that are the two most disparate in terms of nuclear vs cytoplasmic localization of NS5 identified the last 18 amino acid residues of the ~900 amino-acid residues long protein to be responsible for subcellular localization. Because this region is very flexible and not easily seen in crystal structures of DENV NS5, co-crystals of the newly discovered peptide region with importin α were obtained. Structure-based mutations introduced into a DENV2 infectious clone showed that the proline to threonine at position 884 resulted in NS5 being mostly cytoplasmic without affecting virus replication. However mutation of arginine 888, which is conserved in all flaviviruses, to alanine resulted in a completely non-viable virus, suggesting that the C-terminal region is essential for NS5 function irrespective of its role in subcellular location.

Regulation of human adenovirus alternative RNA splicing by the adenoviral L4-33K and L4-22K proteins

Adenovirus makes extensive use of alternative RNA splicing to produce a complex set of spliced viral mRNAs. Studies aimed at characterizing the interactions between the virus and the host cell RNA splicing machinery have identified three viral proteins of special significance for the control of late viral gene expression: L4-33K, L4-22K, and E4-ORF4. L4-33K is a viral alternative RNA splicing factor that controls L1 alternative splicing via an interaction with the cellular protein kinases Protein Kinase A (PKA) and DNA-dependent protein kinase (DNA-PK). L4-22K is a viral transcription factor that also has been implicated in the splicing of a subset of late viral mRNAs. E4-ORF4 is a viral protein that binds the cellular protein phosphatase IIA (PP2A) and controls Serine/Arginine (SR)-rich protein activity by inducing SR protein dephosphorylation. The L4-33K, and most likely also the L4-22K protein, are highly phosphorylated in vivo. Here we will review the function of these viral proteins in the post-transcriptional control of adenoviral gene expression and further discuss the significance of potential protein kinases phosphorylating the L4-33K and/or L4-22K proteins.

Proteome analysis of adenovirus using mass spectrometry

Analysis of proteins and their posttranslational modifications is important for understanding different biological events. For analysis of viral proteomes, an optimal protocol includes production of a highly purified virus that can be investigated with a high-resolving analytical method. In this Methods in Molecular Biology paper we describe a working strategy for how structural proteins in the Adenovirus particle can be studied using liquid chromatography-high-resolving mass spectrometry. This method provides information on the chemical composition of the virus particle. Further, knowledge about amino acids carrying modifications that could be essential for any part of the virus life cycle is collected. We describe in detail alternatives available for preparation of virus for proteome analysis as well as choice of mass spectrometric instrumentation suitable for this kind of analysis.

ViralPhos: incorporating a recursively statistical method to predict phosphorylation sites on virus proteins

Background

The phosphorylation of virus proteins by host kinases is linked to viral replication. This leads to an inhibition of normal host-cell functions. Further elucidation of phosphorylation in virus proteins is required in order to aid in drug design and treatment. However, only a few studies have investigated substrate motifs in identifying virus phosphorylation sites. Additionally, existing bioinformatics tool do not consider potential host kinases that may initiate the phosphorylation of a virus protein.

Results

329 experimentally verified phosphorylation fragments on 111 virus proteins were collected from virPTM. These were clustered into subgroups of significantly conserved motifs using a recursively statistical method. Two-layered Support Vector Machines (SVMs) were then applied to train a predictive model for the identified substrate motifs. The SVM models were evaluated using a five-fold cross validation which yields an average accuracy of 0.86 for serine, and 0.81 for threonine. Furthermore, the proposed method is shown to perform at par with three other phosphorylation site prediction tools: PPSP, KinasePhos 2.0 and GPS 2.1.

Conclusion

In this study, we propose a computational method, ViralPhos, which aims to investigate virus substrate site motifs and identify potential phosphorylation sites on virus proteins. We identified informative substrate motifs that matched with several well-studied kinase groups as potential catalytic kinases for virus protein substrates. The identified substrate motifs were further exploited to identify potential virus phosphorylation sites. The proposed method is shown to be capable of predicting virus phosphorylation sites and has been implemented as a web server http://csb.cse.yzu.edu.tw/ViralPhos/.

Post translational modifications in adenovirus type 2

We have combined 2-D SDS-PAGE with liquid chromatography-high resolving mass spectrometry (LC-MS) to explore the proteome of the adenovirus type 2 (Ad2) at the level of post translational modifications (PTMs). The experimental design included in-solution digestion, followed by titanium dioxide enrichment, as well as in-gel digestion of polypeptides after separation of Ad2 capsid proteins by 1-D and 2-D SDS-PAGE. All samples were analyzed using LC-MS with subsequent manual verification of PTM positions. The results revealed new phosphorylation sites that can explain the observed trains of protein spots observed for the pIII, pIIIa and pIV proteins. The pIIIa protein was found to be the most highly modified protein with now 18 verified sites of phosphorylation, three sites of nitrated tyrosine and one sulfated tyrosine. Nitrated tyrosines were also identified in pII. Lysine acetylations were detected in pII and pVI. The findings make the Ad2 virion much more complex than hitherto believed.

The phosphoproteome of the adenovirus type 2 virion

We have used a proteomics approach to identify sites of phosphorylation in the structural proteins of the Adenovirus type 2 particle. This protein modification might play an important role during infection. Peptides from highly purified virus were enriched for phosphorylations and analyzed by liquid chromatography-high-resolving mass spectrometry. Phosphorylations were identified in 11 structural peptides and 29 non-redundant phosphorylation sites were unambiguously assigned to specific amino acid. An unexpected result was the finding of phosphotyrosine in two of the viral polypeptides. The most highly phosphorylated protein was pIIIa with 12 identified phosphorylation sites. An identified preference for proline or leucine residue flanking the phosphorylation sites downstream suggests that cellular kinases are involved in many of the phosphorylations. Structural modeling showed that one site in the hexon is located on the outer side of the virus and could be of importance for the virus when attaching and entering cells.

Virtual interactomics of proteins from biochemical standpoint

Virtual interactomics represents a rapidly developing scientific area on the boundary line of bioinformatics and interactomics. Protein-related virtual interactomics then comprises instrumental tools for prediction, simulation, and networking of the majority of interactions important for structural and individual reproduction, differentiation, recognition, signaling, regulation, and metabolic pathways of cells and organisms. Here, we describe the main areas of virtual protein interactomics, that is, structurally based comparative analysis and prediction of functionally important interacting sites, mimotope-assisted and combined epitope prediction, molecular (protein) docking studies, and investigation of protein interaction networks. Detailed information about some interesting methodological approaches and online accessible programs or databases is displayed in our tables. Considerable part of the text deals with the searches for common conserved or functionally convergent protein regions and subgraphs of conserved interaction networks, new outstanding trends and clinically interesting results. In agreement with the presented data and relationships, virtual interactomic tools improve our scientific knowledge, help us to formulate working hypotheses, and they frequently also mediate variously important in silico simulations.

Identifying protein phosphorylation sites with kinase substrate specificity on human viruses

Viruses infect humans and progress inside the body leading to various diseases and complications. The phosphorylation of viral proteins catalyzed by host kinases plays crucial regulatory roles in enhancing replication and inhibition of normal host-cell functions. Due to its biological importance, there is a desire to identify the protein phosphorylation sites on human viruses. However, the use of mass spectrometry-based experiments is proven to be expensive and labor-intensive. Furthermore, previous studies which have identified phosphorylation sites in human viruses do not include the investigation of the responsible kinases. Thus, we are motivated to propose a new method to identify protein phosphorylation sites with its kinase substrate specificity on human viruses. The experimentally verified phosphorylation data were extracted from virPTM – a database containing 301 experimentally verified phosphorylation data on 104 human kinase-phosphorylated virus proteins. In an attempt to investigate kinase substrate specificities in viral protein phosphorylation sites, maximal dependence decomposition (MDD) is employed to cluster a large set of phosphorylation data into subgroups containing significantly conserved motifs. The experimental human phosphorylation sites are collected from Phospho.ELM, grouped according to its kinase annotation, and compared with the virus MDD clusters. This investigation identifies human kinases such as CK2, PKB, CDK, and MAPK as potential kinases for catalyzing virus protein substrates as confirmed by published literature. Profile hidden Markov model is then applied to learn a predictive model for each subgroup. A five-fold cross validation evaluation on the MDD-clustered HMMs yields an average accuracy of 84.93% for Serine, and 78.05% for Threonine. Furthermore, an independent testing data collected from UniProtKB and Phospho.ELM is used to make a comparison of predictive performance on three popular kinase-specific phosphorylation site prediction tools. In the independent testing, the high sensitivity and specificity of the proposed method demonstrate the predictive effectiveness of the identified substrate motifs and the importance of investigating potential kinases for viral protein phosphorylation sites.

Using core hydrophobicity to identify phosphorylation sites of human G protein-coupled receptors

As the most frequent drug target, G protein-coupled receptors (GPCRs) are a large family of seven trans-membrane receptors that sense molecules outside the cell and activate inside signal transduction pathways. The activity and lifetime of activated receptors are regulated by receptor phosphorylation. Therefore, investigating the exact positions of phosphorylation sites in GPCRs sequence could provide useful clues for drug design and other biotechnology applications. Experimental identification of phosphorylation sites is expensive and laborious. Hence, there is significant interest in the development of computational methods for reliable prediction of phosphorylation sites from amino acid sequences. In this article, we presented a simple and effective method to recognize phosphorylation sites of human GPCRs by combining amino acid hydrophobicity and support vector machine. The prediction accuracy, sensitivity, specificity, Matthews correlation coefficient and area under the curve values for phosphoserine, phosphothreonine, and phosphotyrosine were 0.964, 0.790, 0.999, 0.866, 0.941; 0.954, 0.800, 0.985, 0.828, 0.958; and 0.976, 0.820, 0.993, 0.861, 0.959, respectively. The establishment of such a fast and accurate prediction method will speed up the pace of identifying proper GPCRs sites to facilitate drug discovery.

Protein phosphorylation from the perspective of systems biology

Protein phosphorylation pathways emerge as large and interconnected networks, involving mutually activating protein kinases, kinases acting as network nodes by phosphorylating different substrates, and cross-talk of phosphorylation with other post-translational modifications. The complexity of these networks clearly necessitates the use of systems biology approaches. Phosphoproteomics represents the basis for detection of phosphoproteins and phosphorylation sites, but it must be combined with transcriptomics and interactomics in attempts to build in silico phosphorylation networks. This review highlights the implication of phosphorylation in cellular physiology across all domains of life. It focuses particularly on reports of human disease correlated to defects in phosphorylation networks. Brief outline of developments in quantitative mass spectrometry-based proteomics and bioinformatic tools specific for phosphoproteome studies is provided.

DECOD: fast and accurate discriminative DNA motif finding

MOTIVATION

Motif discovery is now routinely used in high-throughput studies including large-scale sequencing and proteomics. These datasets present new challenges. The first is speed. Many motif discovery methods do not scale well to large datasets. Another issue is identifying discriminative rather than generative motifs. Such discriminative motifs are important for identifying co-factors and for explaining changes in behavior between different conditions.

RESULTS

To address these issues we developed a method for DECOnvolved Discriminative motif discovery (DECOD). DECOD uses a k-mer count table and so its running time is independent of the size of the input set. By deconvolving the k-mers DECOD considers context information without using the sequences directly. DECOD outperforms previous methods both in speed and in accuracy when using simulated and real biological benchmark data. We performed new binding experiments for p53 mutants and used DECOD to identify p53 co-factors, suggesting new mechanisms for p53 activation.

AVAILABILITY

The source code and binaries for DECOD are available at http://www.sb.cs.cmu.edu/DECOD CONTACT: zivbj@cs.cmu.edu

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

Phospho.ELM: a database of phosphorylation sites--update 2011

The Phospho.ELM resource (http://phospho.elm.eu.org) is a relational database designed to store in vivo and in vitro phosphorylation data extracted from the scientific literature and phosphoproteomic analyses. The resource has been actively developed for more than 7 years and currently comprises 42 574 serine, threonine and tyrosine non-redundant phosphorylation sites. Several new features have been implemented, such as structural disorder/order and accessibility information and a conservation score. Additionally, the conservation of the phosphosites can now be visualized directly on the multiple sequence alignment used for the score calculation. Finally, special emphasis has been put on linking to external resources such as interaction networks and other databases.