Integrated view of the human chromosome X-centric proteome project

Analysis of the phosphorylome of trichoderma reesei cultivated on sugarcane bagasse suggests post-translational regulation of the secreted glycosyl hydrolase Cel7A

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Phosphorylome of Trichoderma reesei reveals phosphosites in some glycosyl hydrolases.

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Phosphoserine and phosphothreonine is the major phosphosites identified.

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Protein Kinase C is the most frequently predicted kinase in phosphorylome.

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The cellulase Cel7A activity is affected by dephosphorylation.

Trichoderma reesei is one of the major producers of holocellulases. It is known that in T. reesei, protein production patterns can change in a carbon source-dependent manner. Here, we performed a phosphorylome analysis of T. reesei grown in the presence of sugarcane bagasse and glucose as carbon source. In presence of sugarcane bagasse, a total of 114 phosphorylated proteins were identified. Phosphoserine and phosphothreonine corresponded to 89.6% of the phosphosites and 10.4% were related to phosphotyrosine. Among the identified proteins, 65% were singly phosphorylated, 19% were doubly phosphorylated, 12% were triply phosphorylated, and 4% displayed even higher phosphorylation. Seventy-five kinases were predicted to phosphorylate the sites identified in this work, and the most frequently predicted serine/threonine kinase was PKC1. Among phosphorylated proteins, four glycosyl hydrolases were predicted to be secreted. Interestingly, Cel7A activity, the most secreted protein, was reduced to approximately 60% after in vitro dephosphorylation, suggesting that phosphorylation might alter Cel7A structure, substrate affinity, and targeting of the substrate to its carbohydrate-binding domain. These results suggest a novel post-translational regulation of Cel7A.

Screening of missing proteins in the human liver proteome by improved MRM-approach-based targeted proteomics

To completely annotate the human genome, the task of identifying and characterizing proteins that currently lack mass spectrometry (MS) evidence is inevitable and urgent. In this study, as the first effort to screen missing proteins in large scale, we developed an approach based on SDS-PAGE followed by liquid chromatography-multiple reaction monitoring (LC-MRM), for screening of those missing proteins with only a single peptide hit in the previous liver proteome data set. Proteins extracted from normal human liver were separated in SDS-PAGE and digested in split gel slice, and the resulting digests were then subjected to LC-schedule MRM analysis. The MRM assays were developed through synthesized crude peptides for target peptides. In total, the expressions of 57 target proteins were confirmed from 185 MRM assays in normal human liver tissues. Among the proved 57 one-hit wonders, 50 proteins are of the minimally redundant set in the PeptideAtlas database, 7 proteins even have none MS-based information previously in various biological processes. We conclude that our SDS-PAGE-MRM workflow can be a powerful approach to screen missing or poorly characterized proteins in different samples and to provide their quantity if detected. The MRM raw data have been uploaded to ISB/SRM Atlas/PASSEL (PXD000648).

MOPED enables discoveries through consistently processed proteomics data

The Model Organism Protein Expression Database (MOPED, http://moped.proteinspire.org) is an expanding proteomics resource to enable biological and biomedical discoveries. MOPED aggregates simple, standardized and consistently processed summaries of protein expression and metadata from proteomics (mass spectrometry) experiments from human and model organisms (mouse, worm, and yeast). The latest version of MOPED adds new estimates of protein abundance and concentration as well as relative (differential) expression data. MOPED provides a new updated query interface that allows users to explore information by organism, tissue, localization, condition, experiment, or keyword. MOPED supports the Human Proteome Project's efforts to generate chromosome- and diseases-specific proteomes by providing links from proteins to chromosome and disease information as well as many complementary resources. MOPED supports a new omics metadata checklist to harmonize data integration, analysis, and use. MOPED's development is driven by the user community, which spans 90 countries and guides future development that will transform MOPED into a multiomics resource. MOPED encourages users to submit data in a simple format. They can use the metadata checklist to generate a data publication for this submission. As a result, MOPED will provide even greater insights into complex biological processes and systems and enable deeper and more comprehensive biological and biomedical discoveries.