pFind Studio: a computational solution for mass spectrometry-based proteomics
2015
Journal of proteome research2015. McClatchy, DB et al.
Scripps Res Inst, Dept Chem Physiol & Mol & Cellular Mol Biol, 10550 North Torrey Pines Rd, La Jolla, CA 92037 USA.
ABSTRACT:Quantification of proteomes by mass spectrometry has proven to be useful to study human pathology recapitulated in cellular or animal models of disease. Enriching and quantifying newly synthesized proteins (NSPs) at set time points by mass spectrometry has the potential to identify important early regulatory or expression changes associated with disease states or perturbations. NSP can be enriched from proteomes by employing pulsed introduction of the non-canonical amino acid, azidohomoalanine (AHA). We demonstrate that pulsed introduction of AHA in the feed of mice can label and identify NSP from multiple tissues. Furthermore, we quantitate differences in new protein expression resulting from CRE-LOX initiated knockout of LKB1 in mouse livers. Overall, the PALM strategy allows for the first time in vivo labeling of mouse tissues to differentiate protein synthesis rates at discrete time points.
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Genome research2015. Zhao, HQ et al.
Natl Inst Biol Sci, Beijing 102206, Peoples R China.
ABSTRACT:RNA editing increases transcriptome diversity through post-transcriptional modifications of RNA. Adenosine deaminases that act on RNA (ADARs) catalyze the adenosine-to-inosine (A-to-I) conversion, the most common type of RNA editing in higher eukaryotes. Caenorhabditis elegans has two ADARs, ADR-1 and ADR-2, but their functions remain unclear. Here, we profiled the RNA editomes of C. elegans at different developmental stages of wild-type and ADAR mutants. We developed a new computational pipeline with a "bisulfite-seq-mapping-like" step and achieved a threefold increase in identification sensitivity. A total of 99.5% of the 47,660 A-to-I editing sites were found in clusters. Of the 3080 editing clusters, 65.7% overlapped with DNA transposons in noncoding regions and 73.7% could form hairpin structures. The numbers of editing sites and clusters were highest at the L1 and embryonic stages. The editing frequency of a cluster positively correlated with the number of editing sites within it. Intriguingly, for 80% of the clusters with 10 or more editing sites, almost all expressed transcripts were edited. Deletion of adr-1 reduced the editing frequency but not the number of editing clusters, whereas deletion of adr-2 nearly abolished RNA editing, indicating a modulating role of ADR-1 and an essential role of ADR-2 in A-to-I editing. Quantitative proteomics analysis showed that adr-2 mutant worms altered the abundance of proteins involved in aging and lifespan regulation. Consistent with this finding, we observed that worms lacking RNA editing were short-lived. Taken together, our results reveal a sophisticated landscape of RNA editing and distinct modes of action of different ADARs.
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The Scientific World Journal2015. Deng, Ning et al.
ABSTRACT:Study of complex proteome brings forward higher request for the quantification method using mass spectrometry technology. In this paper, we present a mass spectrometry label-free quantification tool for complex proteomes, called freeQuant, which integrated quantification with functional analysis effectively. freeQuant consists of two well-integrated modules: label-free quantification and functional analysis with biomedical knowledge. freeQuant supports label-free quantitative analysis which makes full use of tandem mass spectrometry (MS/MS) spectral count, protein sequence length, shared peptides, and ion intensity. It adopts spectral count for quantitative analysis and builds a new method for shared peptides to accurately evaluate abundance of isoforms. For proteins with low abundance, MS/MS total ion count coupled with spectral count is included to ensure accurate protein quantification. Furthermore, freeQuant supports the large-scale functional annotations for complex proteomes. Mitochondrial proteomes from the mouse heart, the mouse liver, and the human heart were used to evaluate the usability and performance of freeQuant. The evaluation showed that the quantitative algorithms implemented in freeQuant can improve accuracy of quantification with better dynamic range.
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The Scientific World Journal2015. Deng, Ning et al.
ABSTRACT:Study of complex proteome brings forward higher request for the quantification method using mass spectrometry technology. In this paper, we present a mass spectrometry label-free quantification tool for complex proteomes, called freeQuant, which integrated quantification with functional analysis effectively. freeQuant consists of two well-integrated modules: label-free quantification and functional analysis with biomedical knowledge. freeQuant supports label-free quantitative analysis which makes full use of tandem mass spectrometry (MS/MS) spectral count, protein sequence length, shared peptides, and ion intensity. It adopts spectral count for quantitative analysis and builds a new method for shared peptides to accurately evaluate abundance of isoforms. For proteins with low abundance, MS/MS total ion count coupled with spectral count is included to ensure accurate protein quantification. Furthermore, freeQuant supports the large-scale functional annotations for complex proteomes. Mitochondrial proteomes from the mouse heart, the mouse liver, and the human heart were used to evaluate the usability and performance of freeQuant. The evaluation showed that the quantitative algorithms implemented in freeQuant can improve accuracy of quantification with better dynamic range.
Use: pFind
Analyst2015. Fang, P et al.
Fudan Univ, Minhang Hosp, Shanghai 201199, Peoples R China.
ABSTRACT:Trypsin has traditionally been used for enzymatic digestion during sample preparation in shotgun proteomics. The stringent specificity of trypsin is essential for accurate protein identification and quantification. But nonspecific trypsin cleavages are often observed in LC-MS/MS-based shotgun proteomics. To explore the extent of nonspecific trypsin cleavages, a series of biological systems including a standard protein mixture, Saccharomyces cerevisiae, human serum, human cancer cell lines and mouse brain were examined. We found that nonspecific trypsin cleavages commonly occurred in various trypsin digested samples with high frequency. To control these nonspecific trypsin cleavages, we optimized fundamental parameters during sample preparation with mouse brain homogenates. These parameters included denaturing agents and protein storage time, trypsin type, enzyme-to-substrate ratio, as well as protein concentration during digestion. The optimized experimental conditions significantly decreased the ratio of partially tryptic peptides in total identifications from 28.4% to 2.8%. Furthermore, the optimized digestion protocol was applied to the study of N-glycoproteomics, and the proportions of partially tryptic peptides in enriched mixtures were also sharply reduced. Our work demonstrates the importance of controlling nonspecific trypsin cleavages in both shotgun proteomics and glycoproteomics and provides a better understanding and standardization for routine proteomics sample treatment.
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Proteomics2015. Zhang, Shen et al.
Chinese Acad Sci, Dalian Inst Chem Phys, Natl Chromatog Res & Anal Ctr, Key Lab,Separat Sci Analyt Chem, Dalian 116023, Peoples R China
ABSTRACT:The isobaric peptide termini labeling (IPTL) method is a promising strategy in quantitative proteomics for its high accuracy, while the increased complexity of MS2 spectra originated from the paired b, y ions has adverse effect on the identification and the coverage of quantification. Here, a paired ions scoring algorithm (PISA) based on Morpheus, a database searching algorithm specifically designed for high-resolution MS2 spectra, was proposed to address this issue. PISA was first tested on two 1:1 mixed IPTL datasets, and increases in peptide to spectrum matchings, distinct peptides and protein groups compared to Morpheus itself and MASCOT were shown. Furthermore, the quantification is simultaneously performed and 100% quantification coverage is achieved by PISA since each of the identified peptide to spectrum matchings has several pairs of fragment ions which could be used for quantification. Then the PISA was applied to the relative quantification of human hepatocellular carcinoma cell lines with high and low metastatic potentials prepared by an IPTL strategy.
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Talanta2015. Xia, SM et al.
Chinese Acad Sci, Dalian Inst Chem Phys, Natl Chromatog R&A Ctr, Dalian 116023, Peoples R China.
ABSTRACT:In this work, a novel integrated sample preparation device for SDS-assisted proteome analysis was developed, by which proteins dissolved in 4% (w/v) SDS were first diluted by 50% methanol, and then SDS was online removed by a hollow fiber membrane interface (HFMI) with 50 mM ammonium bicarbonate (pH 8.0) as an exchange buffer, finally digested by an immobilized enzyme reactor (IMER). To evaluate the performance of such an integrated device, bovine serum albumin dissolved in 4% (w/v) SDS as a model sample was analyzed; it could be found that similar to that obtained by direct analysis of BSA digests without SDS (the sequence coverage of 60.3 +/- 1.0%, n=3), with HFMI as an interface for SDS removal, BSA was identified with the sequence coverage of 61.0 +/- 1.0% (n=3). However, without SDS removal by HFMI, BSA could not be digested by the IMER and none peptides could be detected. In addition, such an integrated sample preparation device was also applied for the analysis of SDS extracted proteins from rat brain, compared to those obtained by filter-aided sample preparation (FASP), not only the identified protein group and unique peptide number were increased by 12% and 39% respectively, but also the sample pretreatment time was shortened from 24 h to 4 h. All these results demonstrated that such an integrated sample preparation device would provide an alternative tool for SDS assisted proteome analysis. (C) 2015 Elsevier B.V. All rights reserved.
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Chinese Chemical Letters2015. Xia, SM et al.
Chinese Acad Sci, Dalian Inst Chem Phys, Natl Chromatog R&A Ctr, Dalian 116023, Peoples R China.
ABSTRACT:In this work, a novel kind of particulate capillary precolumns with double-end polymer monolithic frits has been developed. Firstly, the polymer monolithic frit at one end was prepared via photo-initiated polymerization of a mixture of lauryl methacrylate and ethyleneglycol dimethacrylate with 1-propanol and 1,4-butanediol as porogens and 2,2-dimethoxy-2-phenylacetophenone as a photo-initiator in UV transparent coating capillary (100 mu m i.d.). Subsequently, C18 particles (5 mu m, 100 angstrom) were packed into the capillary, and sealed with the polymer monolithic frit at another end. To prevent the reaction of monomers and C18 particles, the packed C18 particles were masked during UV exposure. The loading capacity of such a precolumn was determined to be about 9 mu g by frontal analysis with a synthetic peptide APGDRIYVHPF as a model sample. Furthermore, two parallel precolumns were incorporated into a two-dimensional nano-liquid chromatography (2D nano-LC) system with dual capillary trap columns for peptide trapping and concentration. Compared to 2D nano-LC system with a single trap column, such two dimensional separations could be operated simultaneously to improve the analysis throughput. All these results demonstrated that such capillary precolumns with double frits would be promising for high-throughput proteome analysis. (C) 2015 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.
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The Federation of European Biochemical Societies Journal2015. Kloet, SL et al.
Dept Mol Biol, M850-3-79 259 RIMLS,POB 9101, NL-6500 HB Nijmegen, Netherlands.
ABSTRACT:The nucleosome remodeling and deacetylase (NuRD) complex is an evolutionarily conserved chromatin-associated protein complex. Although the subunit composition of the mammalian complex is fairly well characterized, less is known about the stability and dynamics of these interactions. Furthermore, detailed information regarding protein-protein interaction surfaces within the complex is still largely lacking. Here, we show that the NuRD complex interacts with a number of substoichiometric zinc finger-containing proteins. Some of these interactions are salt-sensitive (ZNF512B and SALL4), whereas others (ZMYND8) are not. The stoichiometry of the core subunits is not affected by high salt concentrations, indicating that the core complex is stabilized by hydrophobic interactions. Interestingly, the RBBP4 and RBBP7 proteins are sensitive to high nonionic detergent concentrations during affinity purification. In a subunit exchange assay with stable isotope labeling by amino acids in cell culture (SILAC)-treated nuclear extracts, RBBP4 and RBBP7 were identified as dynamic core subunits of the NuRD complex, consistent with their proposed role as histone chaperones. Finally, using cross-linking MS, we have uncovered novel features of NuRD molecular architecture that complement our affinity purification-MS/MS data. Altogether, these findings extend our understanding of MBD3-NuRD structure and stability. Structured digital abstract MBD3 physically interacts with ZNF512B, HDAC1, ZMYND8, GATAD2B, SALL4, GATAD2A, ZNF592, MTA3, ZNF687, CDK2AP1, CHD3, ZNF532, HDAC2, MTA2, CHD4, MTA1, KPNA2, CHD5, RBBP4 and RBBP7 by pull down (View interaction) CDK2AP1 physically interacts with MBD3, MTA3, HDAC2, GATAD2A, CHD4, CDK2AP1, MTA2, HDAC1, MTA1, CHD3, GATAD2B, MBD2, RBBP4 and RBBP7 by pull down (View interaction) MBD3 physically interacts with MTA2, MTA3, RBBP4, RBBP7, HDAC2, HDAC1, CHD4, CHD3 and MTA1 by cross-linking study (View interaction)
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Molecular Cell2015. Sekine, S et al.
RIKEN Syst & Struct Biol Ctr, Tsurumi Ku, 1-7-22 Suehiro Cho, Yokohama, Kanagawa 2300045, Japan.
ABSTRACT:DNA-dependent RNA polymerase (RNAP) accomplishes multiple tasks during transcription by assuming different structural forms. Reportedly, the "tight" form performs nucleotide addition to nascent RNA, while the "ratcheted" form is adopted for transcription inhibition. In this study, we performed Cys-pair crosslinking (CPX) analyses of various transcription complexes of a bacterial RNAP and crystallographic analyses of its backtracked and Gre-factor-bound states to clarify which of the two forms is adopted. The ratcheted form was revealed to support GreA-dependent transcript cleavage, long backtracking, hairpin-dependent pausing, and termination. In contrast, the tight form correlated with nucleotide addition, mismatch-dependent pausing, one-nucleotide backtracking, and factor-independent transcript cleavage. RNAP in the paused/backtracked state, but not the nucleotide-addition state, readily transitions to the ratcheted form ("ratchetable"), indicating that the tight form represents two distinct regulatory states. The 30 end and the hairpin structure of the nascent RNA promote the ratchetable nature by modulating the trigger-loop conformation.
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