Project description:The methylation of histidine residues is increasingly found to be both prevalent throughout the proteome, and also relevant to human disease. Hpm1p mono-methylates H243 in the ribosomal protein Rpl3 and represents the only histidine methyltransferase in Saccharomyces cerevisiae. Interestingly, the hpm1 deletion strain is highly pleiotropic, with many extra-ribosomal phenotypes including improved growth rates in alternative carbon sources. Here we aimed to understand how methylation of one histidine in one ribosomal protein could result in such diverse phenotypes by combining targeted mass spectrometry, growth assays, quantitative proteomics and cross-linking mass spectrometry. We confirmed the localisation and stoichiometry of the H243 site, found unreported sensitivities of Δhpm1 yeast to non-ribosomal stressors, and identified thirty differentially-abundant proteins upon hpm1 knockout, most with clear links to the coordination of sugar metabolism. We adapted the emerging technique of quantitative large scale cross-linking mass spectrometry for use in budding yeast, which resulted in the identification of 1,267 unique in vivo lysine-lysine pairs. By reproducibly monitoring over 350, we detected changes to membrane protein structure, chromatin compaction, and mitochondrial protein-protein interactions, independently of changes in protein abundance themselves. Taken together, these studies reveal a clear role for Hpm1p in the coordination of sugar metabolism, contextualise the deletion strain’s pleiotropy and illustrate how cross-linking mass spectrometry can generate mechanistic insights into complex cellular processes.
Project description:RNA-protein interactions are central to biological regulation. Cross-linking immunoprecipitation (CLIP)-seq is a powerful tool for genome-wide interrogation of RNA-protein interactomes, but current CLIP methods are limited by challenging biochemical steps and fail to detect many classes of noncoding and non-human RNAs. Here we present FAST-iCLIP, an integrated pipeline with improved CLIP biochemistry and an automated informatic pipeline for comprehensive analysis across protein coding, noncoding, repetitive, retroviral, and non-human transcriptomes. FAST-iCLIP of Poly-C binding protein 2 (PCBP2) showed that PCBP2 bound CU-rich motifs in different topologies to recognize mRNAs and noncoding RNAs with distinct biological functions. FAST-iCLIP of PCBP2 in hepatitis C virus-infected cells enabled a joint analysis of the PCBP2 interactome with host and viral RNAs and their interplay. These results show that FAST-iCLIP can be used to rapidly discover and decipher mechanisms of RNA-protein recognition across the diversity of human and pathogen RNAs.
Project description:Kaposi's sarcoma-associated herpesvirus (KSHV) ORF57 is a viral RNA-binding protein essential for viral lytic gene expression. ORF57 binds to target RNA directly via interaction with cellular cofactors. To investigate the entire repertoire of ORF57-associated RNAs we performed UV cross-linking immunoprecipitatin (CLIP) experiment using an affinity-purified, highly specific anti-ORF57 antibody in KSHV-infected primariy effusion lymphoma BCBL-1 cells undegoing lytic virus replication.
Project description:Purpose: Pre-ribosomal RNA is cleaved at defined sites to release the mature ribosomal RNAs, but the functions of many ribosome biogenesis factors involved in 18S rRNA release are not known. We apply an in vivo cross-linking technique coupled with deep sequencing (CRAC) that captures transcriptome-wide interactions between the yeast PIN domain protein Utp23 and its targets in a living cell. Methods: We apply CRAC to an HTP-tagged Utp23 protein (HTP: His6 - TEV cleavage site - two copies of the z-domain of Protein A) in budding yeast. At least two independent experiments were performed and analysed separately. A non-tagged yeast strain was also used as a negative control. Results: We found that yeast Utp23 UV-crosslinked in vivo to the snR30 snoRNA and to the eukaryotic-specific expansion segment 6 (ES6) in the 18S rRNA. Conclusion: According to our crosslinking data, Utp23 is perfectly positioned to coordinate release of the snR30 snoRNA from the 18S ES6 region.
Project description:Reanalysis of a cross-linked ribosomal cellular fraction dataset, that is a subset of a fragmentation parameters optimization dataset (PRIDE project PXD006131). The HCD fragmented part of the dataset was searched with the Cross-Linking MS identification tools OpenPepXL, pLink2, Kojak and XiSearch.
Project description:RNA-protein interactions are central to biological regulation. Cross-linking immunoprecipitation (CLIP)-seq is a powerful tool for genome-wide interrogation of RNA-protein interactomes, but current CLIP methods are limited by challenging biochemical steps and fail to detect many classes of noncoding and non-human RNAs. Here we present FAST-iCLIP, an integrated pipeline with improved CLIP biochemistry and an automated informatic pipeline for comprehensive analysis across protein coding, noncoding, repetitive, retroviral, and non-human transcriptomes. FAST-iCLIP of Poly-C binding protein 2 (PCBP2) showed that PCBP2 bound CU-rich motifs in different topologies to recognize mRNAs and noncoding RNAs with distinct biological functions. FAST-iCLIP of PCBP2 in hepatitis C virus-infected cells enabled a joint analysis of the PCBP2 interactome with host and viral RNAs and their interplay. These results show that FAST-iCLIP can be used to rapidly discover and decipher mechanisms of RNA-protein recognition across the diversity of human and pathogen RNAs. Characterization of non-coding and pathogen RNA-protein interactions using an automated computational pipeline and improved iCLIP biochemistry
Project description:In vivo cross-linking and ribonucleoprotein-immunopurification experiments followed by microarray analysis of bound RNAs (X-RIP-chip). Cells expressing recombinant tandem-affinity purification (TAP)-tagged Trf4 protein were cross-linked with formaldehyde, and Trf4-containing ribonucleoprotein complexes were recovered by affinity selection on IgG-coupled beads (see linked protocol). As a control for non-specifically enriched RNAs, the same experiment was done with untagged WT cells and with cells expressing Fpr1-TAP, a peptidyl-prolyl-cis-trans-isomerase not expected to bind RNA. Set of arrays organized by shared biological context, such as organism, tumors types, processes, etc. Antigenic peptide used in IP: Protein A derivative Computed
Project description:Chemical cross-linking coupled to mass spectrometry was used to study the complex between the ribosomal protein, eS26A, and the escortin, Tsr2. Cross-linking was performed using different cross-linking chemistries: (1) disuccinimidyl suberate (DSS); (2) a combination of adipic acid dihydrazide (ADH) and the coupling reagent, DMTMM; (3) a combination of pimelic acid dihydrazide (PDH) and the coupling reagent, DMTMM.