PupDB: a database of pupylated proteins

Background

Figures of phylogenetic trees are widely used to illustrate the result of evolutionary analyses. However, one cannot easily extract a machine-readable representation from such images. Therefore, new software emerges that helps to preserve phylogenies digitally for future research.

Results

TreeSnatcher Plus is a GUI-driven JAVA application that semi-automatically generates a Newick format for multifurcating, arbitrarily shaped, phylogenetic trees contained in pixel images. It offers a range of image pre-processing methods and detects the topology of a depicted tree with adequate user assistance. The user supervises the recognition process, makes corrections to the image and to the topology and repeats steps if necessary. At the end TreeSnatcher Plus produces a Newick tree code optionally including branch lengths for rectangular and freeform trees.

Conclusions

Although illustrations of phylogenies exist in a vast number of styles, TreeSnatcher Plus imposes no limitations on the images it can process with adequate user assistance. Given that a fully automated digitization of all figures of phylogenetic trees is desirable but currently unrealistic, TreeSnatcher Plus is the only program that reliably facilitates at least a semi-automatic conversion from such figures into a machine-readable format.     

RIBOi: a database for ribosome-interacting proteins

Antibiotics have been widely applied as effective agents for curing infectious diseases caused by pathogenic bacteria. However, the emergence of antibiotic resistance shows a growing threat to the effectiveness of clinical applications of antibiotics. To overcome this challenge, identifying new promising targets for drug development is now urgently needed. The inhibition of translation process is one of the most important mechanisms for many of the existing antibiotics. Meanwhile, ribosome is a universal translational machine in all living cells. It can link amino acids together through the guiding of mRNAs, functioning as the workplace of protein synthesis or translation. Targeting the regulation of ribosomal function and ribosome assembly is an attracting solution for identifying novel targets for antibiotic development. These targets are very critical for developing antibiotics with new mode of action, thus, holds the promise for tackling the ever-growing crisis of bacterial drug resistance.     

ADME-AP: a database of ADME associated proteins

Drug absorption, distribution, metabolism and excretion (ADME) often involve interaction of a drug with specific proteins. Knowledge about these ADME-associated proteins is important in facilitating the study of the molecular mechanism of disposition and individual response as well as therapeutic action of drugs. It is also useful in the development and testing of pharmacokinetics prediction tools. Several databases describing specific classes of ADME-associated proteins have appeared. A new database, ADME-associated proteins (ADME-AP), is introduced to provide comprehensive information about all classes of ADME-associated proteins described in the literature including physiological function of each protein, pharmacokinetic effect, ADME classification, direction and driving force of disposition, location and tissue distribution, substrates, synonyms, gene name and protein availability in other species. Cross-links to other databases are also provided to facilitate the access of information about the sequence, 3D structure, function, polymorphisms, genetic disorders, nomenclature, ligand binding properties and related literatures of each protein. ADME-AP currently contains entries for 321 proteins and 964 substrates.     

cuticleDB: a relational database of Arthropod cuticular proteins

Background  

The insect exoskeleton or cuticle is a bi-partite composite of proteins and chitin that provides protective, skeletal and structural functions. Little information is available about the molecular structure of this important complex that exhibits a helicoidal architecture. Scores of sequences of cuticular proteins have been obtained from direct protein sequencing, from cDNAs, and from genomic analyses.     

O-GLYCBASE: a revised database of O-glycosylated proteins.

O-GLYCBASE is a comprehensive database of information on glycoproteins and their O-linked glycosylation sites. Entries are compiled and revised from the SWISS-PROT and PIR databases as well as directly from recently published reports. Nineteen percent of the entries extracted from the databases needed revision with respect to O-linked glycosylation. Entries include information about species, sequence, glycosylation site and glycan type, and are fully referenced. Sequence logos displaying the acceptor specificity for the GaINAc transferase are shown. A neural network method for prediction of mucin type O-glycosylation sites in mammalian glycoproteins exclusively from the primary sequence is made available by E-mail or WWW. The O-GLYCBASE database is also available electronically through our WWW server or by anonymous FTP.     

DEPD: a novel database for differentially expressed proteins

SUMMARY: The Differentially Expressed Protein Database was designed to store the output of comparative proteomics studies and provides a publicly available query and analysis platform for data mining. The database contains information about more than 3000 differentially expressed proteins (DEPs) manually extracted from the published literature, including relevant biological, experimental and methodological elements. Tools for visualization and functional analysis of DEPs are provided via a user-friendly webinterface. AVAILABILITY: http://protchem.hunnu.edu.cn/depd/.     

Tandem affinity purification and mass spectrometric analysis of ubiquitylated proteins in Arabidopsis

Protein ubiquitylation is a central regulatory mechanism that controls numerous processes in plants, including hormone signaling, developmental progression, responses to biotic and abiotic challenges, protein trafficking and chromatin structure. Despite data implicating thousands of plant proteins as targets, so far only a few have been conclusively shown to be ubiquitylated in planta . Here we describe a method to isolate ubiquitin–protein conjugates from Arabidopsis that exploits a stable transgenic line expressing a synthetic poly- UBQ gene encoding ubiquitin (Ub) monomers N-terminally tagged with hexahistidine. Following sequential enrichment by Ub-affinity and nickel chelate-affinity chromatography, the ubiquitylated proteins were trypsinized, separated by two-dimensional liquid chromatography, and analyzed by mass spectrometry. Our list of 54 non-redundant targets, expressed by as many as 90 possible isoforms, included those predicted by genetic studies to be ubiquitylated in plants (EIN3 and JAZ6) or shown to be ubiquitylated in other eukaryotes (ribosomal subunits, elongation factor 1α, histone H1, HSP70 and CDC48), as well as candidates whose control by the Ub/26S proteasome system is not yet appreciated. Ub attachment site(s) were resolved for a subset of these proteins, but surprisingly little sequence consensus was detected, implying that specific residues surrounding the modified lysine are not important determinants for ubiquitylation. We also identified six of the seven available lysine residues on Ub itself as Ub attachment sites, together with evidence for a branched mixed-linkage chain, suggesting that the topologies of Ub chains can be highly complex in plants. Taken together, our method provides a widely applicable strategy to define ubiquitylation in any tissue of intact plants exposed to a wide range of conditions.     

STRING: a database of predicted functional associations between proteins

Functional links between proteins can often be inferred from genomic associations between the genes that encode them: groups of genes that are required for the same function tend to show similar species coverage, are often located in close proximity on the genome (in prokaryotes), and tend to be involved in gene-fusion events. The database STRING is a precomputed global resource for the exploration and analysis of these associations. Since the three types of evidence differ conceptually, and the number of predicted interactions is very large, it is essential to be able to assess and compare the significance of individual predictions. Thus, STRING contains a unique scoring-framework based on benchmarks of the different types of associations against a common reference set, integrated in a single confidence score per prediction. The graphical representation of the network of inferred, weighted protein interactions provides a high-level view of functional linkage, facilitating the analysis of modularity in biological processes. STRING is updated continuously, and currently contains 261 033 orthologs in 89 fully sequenced genomes. The database predicts functional interactions at an expected level of accuracy of at least 80% for more than half of the genes; it is online at http://www.bork.embl-heidelberg.de/STRING/.     

Predictome: a database of putative functional links between proteins

The current deluge of genomic sequences has spawned the creation of tools capable of making sense of the data. Computational and high-throughput experimental methods for generating links between proteins have recently been emerging. These methods effectively act as hypothesis machines, allowing researchers to screen large sets of data to detect interesting patterns that can then be studied in greater detail. Although the potential use of these putative links in predicting gene function has been demonstrated, a central repository for all such links for many genomes would maximize their usefulness. Here we present Predictome, a database of predicted links between the proteins of 44 genomes based on the implementation of three computational methods—chromosomal proximity, phylogenetic profiling and domain fusion—and large-scale experimental screenings of protein–protein interaction data. The combination of data from various predictive methods in one database allows for their comparison with each other, as well as visualization of their correlation with known pathway information. As a repository for such data, Predictome is an ongoing resource for the community, providing functional relationships among proteins as new genomic data emerges. Predictome is available at http://predictome.bu.edu.     

Ubiquilin interacts with ubiquitylated proteins and proteasome through its ubiquitin-associated and ubiquitin-like domains

Mammalian cells acquire tolerance against multiple stressors through the high-level expression of stress-responsible genes. We have previously demonstrated that protein-disulfide isomerase (PDI) together with ubiquilin are up-regulated in response to hypoxia/brain ischemia, and play critical roles in resistance to these damages. We show here that ubiquilin interacts preferentially with poly-ubiquitin chains and 19S proteasome subunits. Taken together, these results suggest that ubiquitin could serve as an adaptor protein that both interacts with PDI and mediates the delivery of poly-ubiquitylated proteins to the proteasome in the cytosol in the vicinity of the endoplasmic reticulum membrane.     

MIPDB: a relational database dedicated to MIP family proteins

BACKGROUND INFORMATION: The MIPs (major intrinsic proteins) constitute a large family of membrane proteins that facilitate the passive transport of water and small neutral solutes across cell membranes. Since water is the most abundant molecule in all living organisms, the discovery of selective water-transporting channels called AQPs (aquaporins) has led to new knowledge on both the physiological and molecular mechanisms of membrane permeability. The MIPs are identified in Archaea, Bacteria and Eukaryota, and the rapid accumulation of new sequences in the database provides an opportunity for large-scale analysis, to identify functional and/or structural signatures or to infer evolutionary relationships. To help perform such an analysis, we have developed MIPDB (database for MIP proteins), a relational database dedicated to members of the MIP family. RESULTS: MIPDB is a motif-oriented database that integrates data on 785 MIP proteins from more than 200 organisms and contains 230 distinct sequence motifs. MIPDB proposes the classification of MIP proteins into three functional subgroups: AQPs, glycerol-uptake facilitators and aquaglyceroporins. Plant MIPs are classified into three specific subgroups according to their subcellular distribution in the plasma membrane, tonoplast or the symbiosome membrane. Some motifs of the database are highly selective and can be used to predict the transport function or subcellular localization of unknown MIP proteins. CONCLUSIONS: MIPDB offers a user-friendly and intuitive interface for a rapid and easy access to MIP resources and to sequence analysis tools. MIPDB is a web application, publicly accessible at http://idefix.univ-rennes1.fr:8080/Prot/index.html.     

CluSTr: a database of clusters of SWISS-PROT+TrEMBL proteins

The CluSTr (Clusters of SWISS-PROT and TrEMBL proteins) database offers an automatic classification of SWISS-PROT and TrEMBL proteins into groups of related proteins. The clustering is based on analysis of all pairwise comparisons between protein sequences. Analysis has been carried out for different levels of protein similarity, yielding a hierarchical organisation of clusters. The database provides links to InterPro, which integrates information on protein families, domains and functional sites from PROSITE, PRINTS, Pfam and ProDom. Links to the InterPro graphical interface allow users to see at a glance whether proteins from the cluster share particular functional sites. CluSTr also provides cross-references to HSSP and PDB. The database is available for querying and browsing at http://www.ebi.ac.uk/clustr.     

DIP: the database of interacting proteins

The Database of Interacting Proteins (DIP; http://dip.doe-mbi.ucla.edu) is a database that documents experimentally determined protein-protein interactions. This database is intended to provide the scientific community with a comprehensive and integrated tool for browsing and efficiently extracting information about protein interactions and interaction networks in biological processes. Beyond cataloging details of protein-protein interactions, the DIP is useful for understanding protein function and protein-protein relationships, studying the properties of networks of interacting proteins, benchmarking predictions of protein-protein interactions, and studying the evolution of protein-protein interactions.     

O-GLYCBASE version 2.0: a revised database of O-glycosylated proteins.

O-GLYCBASE is an updated database of information on glycoproteins and their O-linked glycosylation sites. Entries are compiled and revised from the literature, and from the SWISS-PROT database. Entries include information about species, sequence, glycosylation sites and glycan type. O-GLYCBASE is now fully cross-referenced to the SWISS-PROT, PIR, PROSITE, PDB, EMBL, HSSP, LISTA and MIM databases. Compared with version 1.0 the number of entries have increased by 34%. Revision of the O-glycan assignment was performed on 20% of the entries. Sequence logos displaying the acceptor specificity patterns for the GalNAc, mannose and GlcNAc transferases are shown. The O-GLYCBASE database is available through WWW or by anonymous FTP.     

O-GLYCBASE Version 3.0: a revised database of O-glycosylated proteins.

O-GLYCBASE is a revised database of information on glycoproteins and their O-linked glycosylation sites. Entries are compiled and revised from the literature, and from the sequence databases. Entries include information about species, sequence, glycosylation sites and glycan type and is fully cross-referenced. Compared to version 2.0 the number of entries has increased by 20%. Sequence logos displaying the acceptor specificity patterns for the GalNAc, mannose and GlcNAc transferases are shown. The O-GLYCBASE database is available through the WWW at http://www.cbs.dtu. dk/databases/OGLYCBASE/     

O-GLYCBASE version 4.0: a revised database of O-glycosylated proteins.

O-GLYCBASE is a database of glycoproteins with O-linked glycosylation sites. Entries with at least one experimentally verified O-glycosylation site have been compiled from protein sequence databases and literature. Each entry contains information about the glycan involved, the species, sequence, a literature reference and http-linked cross-references to other databases. Version 4.0 contains 179 protein entries, an approximate 15% increase over the last version. Sequence logos representing the acceptor specificity patterns for GalNAc, GlcNAc, mannosyl and xylosyl transferases are shown. The O-GLYCBASE database is available through the WWW at http://www.cbs.dtu.dk/databases/OGLYCBASE/     

Mammalian Ddi2 is a shuttling factor containing a retroviral protease domain that influences binding of ubiquitylated proteins and proteasomal degradation

Although several proteasome subunits have been shown to bind ubiquitin (Ub) chains, many ubiquitylated substrates also associate with 26S proteasomes via “shuttling factors.” Unlike the well-studied yeast shuttling factors Rad23 and Dsk2, vertebrate homologs Ddi2 and Ddi1 lack a Ub-associated domain; therefore, it is unclear how they bind Ub. Here, we show that deletion of Ddi2 leads to the accumulation of Ub conjugates with K11/K48 branched chains. We found using affinity copurifications that Ddi2 binds Ub conjugates through its Ub-like domain, which is also required for Ddi2 binding to proteasomes. Furthermore, in cell extracts, adding Ub conjugates increased the amount of Ddi2 associated with proteasomes, and adding Ddi2 increased the binding of Ub conjugates to purified proteasomes. In addition, Ddi2 also contains a retroviral protease domain with undefined cellular roles. We show that blocking the endoprotease activity of Ddi2 either genetically or with the HIV protease inhibitor nelfinavir increased its binding to Ub conjugates but decreased its binding to proteasomes and reduced subsequent protein degradation by proteasomes leading to further accumulation of Ub conjugates. Finally, nelfinavir treatment required Ddi2 to induce the unfolded protein response. Thus, Ddi2 appears to function as a shuttling factor in endoplasmic reticulum–associated protein degradation and delivers K11/K48-ubiquitylated proteins to the proteasome. We conclude that the protease activity of Ddi2 influences this shuttling factor activity, promotes protein turnover, and helps prevent endoplasmic reticulum stress, which may explain nelfinavir’s ability to enhance cell killing by proteasome inhibitors.