1
|
SanchesTrevizol J, Dionizio A, Delgado AQ, Ventura TMO, da Silva Ribeiro CF, Rabelo Buzalaf N, Bosqueiro JR, Buzalaf MAR. Optimized protocol for shotgun label-free proteomic analysis of pancreatic islets. Biol Methods Protoc 2024; 9:bpae003. [PMID: 38405023 PMCID: PMC10893585 DOI: 10.1093/biomethods/bpae003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 01/16/2024] [Accepted: 01/23/2024] [Indexed: 02/27/2024] Open
Abstract
Pancreatic islets are crucial in diabetes research. Consequently, this protocol aims at optimizing both the protein-extraction process and the proteomic analysis via shotgun methods for pancreatic islets. Six protocols were tested, combining three types of chemical extraction with two mechanical extraction methods. Furthermore, two protocols incorporated a surfactant to enhance enzymatic cleavage. The steps involved extraction and concentration of protein, protein quantification, reduction, alkylation, digestion, purification and desalination, sample concentration to ∼1 µl, and proteomic analysis using the mass spectrometer. The most effective protocol involves either a milder chemical extraction paired with a more intensive mechanical process, or a more robust chemical extraction paired with a gentle mechanical process, tailored to the sample's characteristics. Additionally, it was observed that the use of a surfactant proved ineffective for these types of samples. Protocol 5 was recently used with success to examine metabolic changes in pancreatic islets of non-obese diabetic mice exposed to low doses of fluoride ions (F-) and the primary pathways altered by the treatment.
Collapse
Affiliation(s)
- Juliana SanchesTrevizol
- Department of Biological Sciences, Bauru School of Dentistry, University of São Paulo, Bauru, Brazil
| | - Aline Dionizio
- Department of Biological Sciences, Bauru School of Dentistry, University of São Paulo, Bauru, Brazil
| | | | | | | | - Nathalia Rabelo Buzalaf
- Department of Biological Sciences, Bauru School of Dentistry, University of São Paulo, Bauru, Brazil
| | - José Roberto Bosqueiro
- Department of Physical Education, Faculty of Science, São Paulo State University, Bauru, São Paulo, Brazil
| | | |
Collapse
|
2
|
Caira S, Picariello G, Renzone G, Arena S, Troise AD, De Pascale S, Ciaravolo V, Pinto G, Addeo F, Scaloni A. Recent developments in peptidomics for the quali-quantitative analysis of food-derived peptides in human body fluids and tissues. Trends Food Sci Technol 2022. [DOI: 10.1016/j.tifs.2022.06.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
|
3
|
Maes E, Oeyen E, Boonen K, Schildermans K, Mertens I, Pauwels P, Valkenborg D, Baggerman G. The challenges of peptidomics in complementing proteomics in a clinical context. MASS SPECTROMETRY REVIEWS 2019; 38:253-264. [PMID: 30372792 DOI: 10.1002/mas.21581] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 10/01/2018] [Indexed: 06/08/2023]
Abstract
Naturally occurring peptides, including growth factors, hormones, and neurotransmitters, represent an important class of biomolecules and have crucial roles in human physiology. The study of these peptides in clinical samples is therefore as relevant as ever. Compared to more routine proteomics applications in clinical research, peptidomics research questions are more challenging and have special requirements with regard to sample handling, experimental design, and bioinformatics. In this review, we describe the issues that confront peptidomics in a clinical context. After these hurdles are (partially) overcome, peptidomics will be ready for a successful translation into medical practice.
Collapse
Affiliation(s)
- Evelyne Maes
- Flemish Institute for Technological Research (VITO), Mol, Belgium
- Centre for Proteomics, University of Antwerp, Antwerp, Belgium
- Food and Bio-Based Products, AgResearch Ltd., Lincoln, New Zealand
| | - Eline Oeyen
- Flemish Institute for Technological Research (VITO), Mol, Belgium
- Centre for Proteomics, University of Antwerp, Antwerp, Belgium
| | - Kurt Boonen
- Flemish Institute for Technological Research (VITO), Mol, Belgium
- Centre for Proteomics, University of Antwerp, Antwerp, Belgium
| | - Karin Schildermans
- Flemish Institute for Technological Research (VITO), Mol, Belgium
- Centre for Proteomics, University of Antwerp, Antwerp, Belgium
| | - Inge Mertens
- Flemish Institute for Technological Research (VITO), Mol, Belgium
- Centre for Proteomics, University of Antwerp, Antwerp, Belgium
| | - Patrick Pauwels
- Molecular Pathology Unit, Department of Pathology, Antwerp University Hospital, Edegem, Belgium
| | - Dirk Valkenborg
- Flemish Institute for Technological Research (VITO), Mol, Belgium
- Centre for Proteomics, University of Antwerp, Antwerp, Belgium
- Center for Statistics, Hasselt University, Diepenbeek, Belgium
| | - Geert Baggerman
- Flemish Institute for Technological Research (VITO), Mol, Belgium
- Centre for Proteomics, University of Antwerp, Antwerp, Belgium
| |
Collapse
|
4
|
Edwards SL, Mergan L, Parmar B, Cockx B, De Haes W, Temmerman L, Schoofs L. Exploring neuropeptide signalling through proteomics and peptidomics. Expert Rev Proteomics 2018; 16:131-137. [DOI: 10.1080/14789450.2019.1559733] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
| | - Lucas Mergan
- Animal Physiology and Neurobiology, Department of Biology, KU Leuven, Leuven, Belgium
| | - Bhavesh Parmar
- Animal Physiology and Neurobiology, Department of Biology, KU Leuven, Leuven, Belgium
| | - Bram Cockx
- Animal Physiology and Neurobiology, Department of Biology, KU Leuven, Leuven, Belgium
| | - Wouter De Haes
- Animal Physiology and Neurobiology, Department of Biology, KU Leuven, Leuven, Belgium
| | - Liesbet Temmerman
- Animal Physiology and Neurobiology, Department of Biology, KU Leuven, Leuven, Belgium
| | - Liliane Schoofs
- Animal Physiology and Neurobiology, Department of Biology, KU Leuven, Leuven, Belgium
| |
Collapse
|
5
|
Leon DR, Ytterberg AJ, Boontheung P, Kim U, Loo JA, Gunsalus RP, Ogorzalek Loo RR. Mining proteomic data to expose protein modifications in Methanosarcina mazei strain Gö1. Front Microbiol 2015; 6:149. [PMID: 25798134 PMCID: PMC4350412 DOI: 10.3389/fmicb.2015.00149] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2014] [Accepted: 02/09/2015] [Indexed: 12/11/2022] Open
Abstract
Proteomic tools identify constituents of complex mixtures, often delivering long lists of identified proteins. The high-throughput methods excel at matching tandem mass spectrometry data to spectra predicted from sequence databases. Unassigned mass spectra are ignored, but could, in principle, provide valuable information on unanticipated modifications and improve protein annotations while consuming limited quantities of material. Strategies to "mine" information from these discards are presented, along with discussion of features that, when present, provide strong support for modifications. In this study we mined LC-MS/MS datasets of proteolytically-digested concanavalin A pull down fractions from Methanosarcina mazei Gö1 cell lysates. Analyses identified 154 proteins. Many of the observed proteins displayed post-translationally modified forms, including O-formylated and methyl-esterified segments that appear biologically relevant (i.e., not artifacts of sample handling). Interesting cleavages and modifications (e.g., S-cyanylation and trimethylation) were observed near catalytic sites of methanogenesis enzymes. Of 31 Methanosarcina protein N-termini recovered by concanavalin A binding or from a previous study, only M. mazei S-layer protein MM1976 and its M. acetivorans C2A orthologue, MA0829, underwent signal peptide excision. Experimental results contrast with predictions from algorithms SignalP 3.0 and Exprot, which were found to over-predict the presence of signal peptides. Proteins MM0002, MM0716, MM1364, and MM1976 were found to be glycosylated, and employing chromatography tailored specifically for glycopeptides will likely reveal more. This study supplements limited, existing experimental datasets of mature archaeal N-termini, including presence or absence of signal peptides, translation initiation sites, and other processing. Methanosarcina surface and membrane proteins are richly modified.
Collapse
Affiliation(s)
- Deborah R Leon
- Department of Chemistry and Biochemistry, University of California, Los Angeles Los Angeles, CA, USA
| | - A Jimmy Ytterberg
- Department of Chemistry and Biochemistry, University of California, Los Angeles Los Angeles, CA, USA
| | - Pinmanee Boontheung
- Department of Chemistry and Biochemistry, University of California, Los Angeles Los Angeles, CA, USA
| | - Unmi Kim
- Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles Los Angeles, CA, USA
| | - Joseph A Loo
- Department of Chemistry and Biochemistry, University of California, Los Angeles Los Angeles, CA, USA ; Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles Los Angeles, CA, USA ; UCLA-DOE Institute for Genomics and Proteomics, University of California, Los Angeles Los Angeles, CA, USA
| | - Robert P Gunsalus
- Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles Los Angeles, CA, USA ; UCLA-DOE Institute for Genomics and Proteomics, University of California, Los Angeles Los Angeles, CA, USA
| | - Rachel R Ogorzalek Loo
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles Los Angeles, CA, USA ; UCLA-DOE Institute for Genomics and Proteomics, University of California, Los Angeles Los Angeles, CA, USA
| |
Collapse
|
6
|
Lambers TT, Gloerich J, van Hoffen E, Alkema W, Hondmann DH, van Tol EA. Clustering analyses in peptidomics revealed that peptide profiles of infant formulae are descriptive. Food Sci Nutr 2014; 3:81-90. [PMID: 25648153 PMCID: PMC4304566 DOI: 10.1002/fsn3.196] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Revised: 11/27/2014] [Accepted: 11/28/2014] [Indexed: 01/05/2023] Open
Abstract
Prompted by the accumulating evidence on bioactive moieties of milk-derived peptides, novel methods were applied to compare the peptide composition among commercially available hydrolysate formulations and to determine batch-to-batch variations of protein hydrolysate products. Despite the availability of general methods to measure, for example, the degree of hydrolysis and peptide mass distribution at a high level, the objective of this study was to more qualitatively compare peptide sequences and composition. By a comprehensive approach combining peptidomics technologies and multivariate clustering analyses, the peptide profiles of different hydrolyzed milk protein formulations were compared. Moreover, peptide profiles of various hydrolysate batches that had been produced over a period of 5 years were included. Coupling of identified peptide sequences to the position in their corresponding milk proteins produced numerical datasets that subsequently were utilized for multivariate data analyses. These analyses revealed that batch-to-batch variation in the peptide profiles of a specific extensively hydrolyzed casein preparation was low. Moreover, extensive multivariate evaluations revealed that the peptide profiles of different commercially available hydrolyzed milk protein formulations provided a descriptive and distinct signature. Overall, the described methodology may contribute to the field of peptide research as observed dissimilarities in peptide profiles of similar products may be related to differences in their overall functionality.
Collapse
Affiliation(s)
- Tim T Lambers
- Mead Johnson Pediatric Nutrition Institute Nijmegen, The Netherlands
| | - Jolein Gloerich
- Radboud Proteomics Center, Department of Laboratory Medicine, Radboud University Medical Center Nijmegen, The Netherlands
| | | | | | - Dirk H Hondmann
- Mead Johnson Pediatric Nutrition Institute Nijmegen, The Netherlands
| | - Eric Af van Tol
- Mead Johnson Pediatric Nutrition Institute Nijmegen, The Netherlands
| |
Collapse
|
7
|
De Haes W, Van Sinay E, Detienne G, Temmerman L, Schoofs L, Boonen K. Functional neuropeptidomics in invertebrates. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2014; 1854:812-26. [PMID: 25528324 DOI: 10.1016/j.bbapap.2014.12.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 11/27/2014] [Accepted: 12/10/2014] [Indexed: 10/24/2022]
Abstract
Neuropeptides are key messengers in almost all physiological processes. They originate from larger precursors and are extensively processed to become bioactive. Neuropeptidomics aims to comprehensively identify the collection of neuropeptides in an organism, organ, tissue or cell. The neuropeptidome of several invertebrates is thoroughly explored since they are important model organisms (and models for human diseases), disease vectors and pest species. The charting of the neuropeptidome is the first step towards understanding peptidergic signaling. This review will first discuss the latest developments in exploring the neuropeptidome. The physiological roles and modes of action of neuropeptides can be explored in two ways, which are largely orthogonal and therefore complementary. The first way consists of inferring the functions of neuropeptides by a forward approach where neuropeptide profiles are compared under different physiological conditions. Second is the reverse approach were neuropeptide collections are used to screen for receptor-binding. This is followed by localization studies and functional tests. This review will focus on how these different functional screening methods contributed to the field of invertebrate neuropeptidomics and expanded our knowledge of peptidergic signaling. This article is part of a Special Issue entitled: Neuroproteomics: Applications in Neuroscience and Neurology.
Collapse
Affiliation(s)
- Wouter De Haes
- Functional Genomics and Proteomics, Department of Biology, University of Leuven (KU Leuven), Naamsestraat 59, 3000 Leuven, Belgium
| | - Elien Van Sinay
- Functional Genomics and Proteomics, Department of Biology, University of Leuven (KU Leuven), Naamsestraat 59, 3000 Leuven, Belgium
| | - Giel Detienne
- Functional Genomics and Proteomics, Department of Biology, University of Leuven (KU Leuven), Naamsestraat 59, 3000 Leuven, Belgium
| | - Liesbet Temmerman
- Functional Genomics and Proteomics, Department of Biology, University of Leuven (KU Leuven), Naamsestraat 59, 3000 Leuven, Belgium
| | - Liliane Schoofs
- Functional Genomics and Proteomics, Department of Biology, University of Leuven (KU Leuven), Naamsestraat 59, 3000 Leuven, Belgium
| | - Kurt Boonen
- Functional Genomics and Proteomics, Department of Biology, University of Leuven (KU Leuven), Naamsestraat 59, 3000 Leuven, Belgium.
| |
Collapse
|
8
|
Nuytens K, Tuand K, Di Michele M, Boonen K, Waelkens E, Freson K, Creemers JW. Platelets of mice heterozygous for neurobeachin, a candidate gene for autism spectrum disorder, display protein changes related to aberrant protein kinase A activity. Mol Autism 2013; 4:43. [PMID: 24188528 PMCID: PMC3829668 DOI: 10.1186/2040-2392-4-43] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Accepted: 10/08/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Neurobeachin (NBEA) has been identified as a candidate gene for autism spectrum disorders (ASD) in several unrelated patients with alterations in the NBEA gene. The exact function of NBEA, a multidomain scaffolding protein, is currently unknown. It contains an A-kinase anchoring protein (AKAP) domain which binds the regulatory subunit of protein kinase A (PKA) thereby confining its activity to specific subcellular regions. NBEA has been implicated in post-Golgi membrane trafficking and in regulated secretion. The mechanism of regulated secretion is largely conserved between neurons and platelets, and the morphology of platelet dense granules was found to be abnormal in several ASD patients, including one with NBEA haploinsufficiency. Platelet dense granules are secreted upon vascular injury when platelets are exposed to for instance collagen. Dense granules contain serotonin, ATP and ADP, which are necessary for platelet plug formation and vascular contraction. METHODS To further investigate possible roles for NBEA in secretion or dense granule morphology, platelets from Nbea+/- mice were analyzed morphometrically, functionally and biochemically. A differential proteomics and peptidomics screen was performed between Nbea+/- and Nbea+/+ mice, in which altered Talin-1 cleavage was further investigated and validated in brain samples. Finally, the phosphorylation pattern of PKA substrates was analyzed. RESULTS Platelet dense granules of Nbea+/- mice had a reduced surface area and abnormal dense-core halo, but normal serotonin-content. Nbea haploinsufficiency did not affect platelet aggregation and ATP secretion after collagen stimulation, although the platelet shape change was more pronounced. Furthermore, peptidomics revealed that Nbea+/- platelets contain significantly reduced levels of several actin-interacting peptides. Decreased levels were detected of the actin-binding head and rod domain of Talin-1, which are cleavage products of Calpain-2. This is most likely due to increased PKA-mediated phosphorylation of Calpain-2, which renders the enzyme less active. Analysis of other PKA substrates revealed both increased and reduced phosphorylation. CONCLUSION Our results show the pleiotropic effects of alterations in PKA activity due to Nbea haploinsufficiency, highlighting the important function of the AKAP domain in Nbea in regulating and confining PKA activity. Furthermore, these results suggest a role for Nbea in remodeling the actin cytoskeleton of platelets.
Collapse
Affiliation(s)
- Kim Nuytens
- Department of Human Genetics, Laboratory for Biochemical Neuroendocrinology, KU Leuven, 3000 Leuven, Belgium.,Leuven Autism Research Consortium (LAuRes), KU Leuven, 3000 Leuven, Belgium
| | - Krizia Tuand
- Department of Human Genetics, Laboratory for Biochemical Neuroendocrinology, KU Leuven, 3000 Leuven, Belgium.,Leuven Autism Research Consortium (LAuRes), KU Leuven, 3000 Leuven, Belgium
| | - Michela Di Michele
- Department of Cardiovascular Sciences, Center for Molecular and Vascular Biology, KU Leuven, 3000 Leuven, Belgium
| | - Kurt Boonen
- Department of Human Genetics, Laboratory for Biochemical Neuroendocrinology, KU Leuven, 3000 Leuven, Belgium
| | - Etienne Waelkens
- Department of Cellular and Molecular Medicine, Laboratory of Protein Phosphorylation and Proteomics, KU Leuven, 3000 Leuven, Belgium
| | - Kathleen Freson
- Leuven Autism Research Consortium (LAuRes), KU Leuven, 3000 Leuven, Belgium.,Department of Cardiovascular Sciences, Center for Molecular and Vascular Biology, KU Leuven, 3000 Leuven, Belgium
| | - John Wm Creemers
- Department of Human Genetics, Laboratory for Biochemical Neuroendocrinology, KU Leuven, 3000 Leuven, Belgium.,Leuven Autism Research Consortium (LAuRes), KU Leuven, 3000 Leuven, Belgium
| |
Collapse
|
9
|
Hayakawa E, Menschaert G, De Bock PJ, Luyten W, Gevaert K, Baggerman G, Schoofs L. Improving the identification rate of endogenous peptides using electron transfer dissociation and collision-induced dissociation. J Proteome Res 2013; 12:5410-21. [PMID: 24032530 DOI: 10.1021/pr400446z] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Tandem mass spectrometry (MS/MS) combined with bioinformatics tools have enabled fast and systematic protein identification based on peptide-to-spectrum matches. However, it remains challenging to obtain accurate identification of endogenous peptides, such as neuropeptides, peptide hormones, peptide pheromones, venom peptides, and antimicrobial peptides. Since these peptides are processed at sites that are difficult to predict reliably, the search of their MS/MS spectra in sequence databases needs to be done without any protease setting. In addition, many endogenous peptides carry various post-translational modifications, making it essential to take these into account in the database search. These characteristics of endogenous peptides result in a huge search space, frequently leading to poor confidence of the peptide characterizations in peptidomics studies. We have developed a new MS/MS spectrum search tool for highly accurate and confident identification of endogenous peptides by combining two different fragmentation methods. Our approach takes advantage of the combination of two independent fragmentation methods (collision-induced dissociation and electron transfer dissociation). Their peptide spectral matching is carried out separately in both methods, and the final score is built as a combination of the two separate scores. We demonstrate that this approach is very effective in discriminating correct peptide identifications from false hits. We applied this approach to a spectral data set of neuropeptides extracted from mouse pituitary tumor cells. Compared to conventional MS-based identification, i.e., using a single fragmentation method, our approach significantly increased the peptide identification rate. It proved also highly effective for scanning spectra against a very large search space, enabling more accurate genome-wide searches and searches including multiple potential post-translational modifications.
Collapse
Affiliation(s)
- Eisuke Hayakawa
- Research Group of Functional Genomics and Proteomics, KU Leuven , Leuven, Belgium
| | | | | | | | | | | | | |
Collapse
|
10
|
Clowers BH, Wunschel DS, Kreuzer HW, Engelmann HE, Valentine N, Wahl KL. Characterization of Residual Medium Peptides from Yersinia pestis Cultures. Anal Chem 2013; 85:3933-9. [DOI: 10.1021/ac3034272] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Brian H. Clowers
- Pacific Northwest National Laboratory, Richland, Washington
99352, United States
| | - David S. Wunschel
- Pacific Northwest National Laboratory, Richland, Washington
99352, United States
| | - Helen W. Kreuzer
- Pacific Northwest National Laboratory, Richland, Washington
99352, United States
| | - Heather E. Engelmann
- Pacific Northwest National Laboratory, Richland, Washington
99352, United States
| | - Nancy Valentine
- Pacific Northwest National Laboratory, Richland, Washington
99352, United States
| | - Karen L. Wahl
- Pacific Northwest National Laboratory, Richland, Washington
99352, United States
| |
Collapse
|
11
|
Yadav AK, Kumar D, Dash D. Learning from decoys to improve the sensitivity and specificity of proteomics database search results. PLoS One 2012. [PMID: 23189209 PMCID: PMC3506577 DOI: 10.1371/journal.pone.0050651] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The statistical validation of database search results is a complex issue in bottom-up proteomics. The correct and incorrect peptide spectrum match (PSM) scores overlap significantly, making an accurate assessment of true peptide matches challenging. Since the complete separation between the true and false hits is practically never achieved, there is need for better methods and rescoring algorithms to improve upon the primary database search results. Here we describe the calibration and False Discovery Rate (FDR) estimation of database search scores through a dynamic FDR calculation method, FlexiFDR, which increases both the sensitivity and specificity of search results. Modelling a simple linear regression on the decoy hits for different charge states, the method maximized the number of true positives and reduced the number of false negatives in several standard datasets of varying complexity (18-mix, 49-mix, 200-mix) and few complex datasets (E. coli and Yeast) obtained from a wide variety of MS platforms. The net positive gain for correct spectral and peptide identifications was up to 14.81% and 6.2% respectively. The approach is applicable to different search methodologies- separate as well as concatenated database search, high mass accuracy, and semi-tryptic and modification searches. FlexiFDR was also applied to Mascot results and showed better performance than before. We have shown that appropriate threshold learnt from decoys, can be very effective in improving the database search results. FlexiFDR adapts itself to different instruments, data types and MS platforms. It learns from the decoy hits and sets a flexible threshold that automatically aligns itself to the underlying variables of data quality and size.
Collapse
Affiliation(s)
- Amit Kumar Yadav
- GNR Knowledge Center for Genome Informatics, CSIR-Institute of Genomics and Integrative Biology, Delhi, India
| | - Dhirendra Kumar
- GNR Knowledge Center for Genome Informatics, CSIR-Institute of Genomics and Integrative Biology, Delhi, India
| | - Debasis Dash
- GNR Knowledge Center for Genome Informatics, CSIR-Institute of Genomics and Integrative Biology, Delhi, India
- * E-mail:
| |
Collapse
|
12
|
Menschaert G, Hayakawa E, Schoofs L, Van Criekinge W, Baggerman G. Spectral Clustering in Peptidomics Studies Allows Homology Searching and Modification Profiling: HomClus, a Versatile Tool. J Proteome Res 2012; 11:2774-85. [DOI: 10.1021/pr201114m] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Gerben Menschaert
- Faculty of Bioscience Engineering,
Laboratory for Bioinformatics and Computational Genomics, Ghent University, Ghent, Belgium
- Prometa, Interfaculty Center for Proteomics
and Metabolomics, K.U. Leuven, Leuven,
Belgium
| | - Eisuke Hayakawa
- Prometa, Interfaculty Center for Proteomics
and Metabolomics, K.U. Leuven, Leuven,
Belgium
- Research Group of
Functional Genomics and Proteomics, K.U. Leuven, 3000 Leuven, Belgium
| | - Liliane Schoofs
- Research Group of
Functional Genomics and Proteomics, K.U. Leuven, 3000 Leuven, Belgium
| | - Wim Van Criekinge
- Faculty of Bioscience Engineering,
Laboratory for Bioinformatics and Computational Genomics, Ghent University, Ghent, Belgium
| | - Geert Baggerman
- VITO Nv, 2400 Mol, Belgium
- CFP, Center for Proteomics, 2020 Antwerpen, Belgium
| |
Collapse
|
13
|
Minerva L, Boonen K, Menschaert G, Landuyt B, Baggerman G, Arckens L. Linking Mass Spectrometric Imaging and Traditional Peptidomics: A Validation in the Obese Mouse Model. Anal Chem 2011; 83:7682-91. [DOI: 10.1021/ac200888j] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
| | | | - G. Menschaert
- BioBix, Laboratory of Bioinformatics and Computational Genomics, Ghent University, 9000 Ghent, Belgium
| | | | | | | |
Collapse
|
14
|
Clustering of MS spectra for improved protein identification rate and screening for protein variants and modifications by MALDI-MS/MS. J Proteomics 2011; 74:1190-200. [DOI: 10.1016/j.jprot.2011.04.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Revised: 03/30/2011] [Accepted: 04/08/2011] [Indexed: 12/11/2022]
|
15
|
Ye D, Fu Y, Sun RX, Wang HP, Yuan ZF, Chi H, He SM. Open MS/MS spectral library search to identify unanticipated post-translational modifications and increase spectral identification rate. ACTA ACUST UNITED AC 2010; 26:i399-406. [PMID: 20529934 PMCID: PMC2881370 DOI: 10.1093/bioinformatics/btq185] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Motivation: Identification of post-translationally modified proteins has become one of the central issues of current proteomics. Spectral library search is a new and promising computational approach to mass spectrometry-based protein identification. However, its potential in identification of unanticipated post-translational modifications has rarely been explored. The existing spectral library search tools are designed to match the query spectrum to the reference library spectra with the same peptide mass. Thus, spectra of peptides with unanticipated modifications cannot be identified. Results: In this article, we present an open spectral library search tool, named pMatch. It extends the existing library search algorithms in at least three aspects to support the identification of unanticipated modifications. First, the spectra in library are optimized with the full peptide sequence information to better tolerate the peptide fragmentation pattern variations caused by some modification(s). Second, a new scoring system is devised, which uses charge-dependent mass shifts for peak matching and combines a probability-based model with the general spectral dot-product for scoring. Third, a target-decoy strategy is used for false discovery rate control. To demonstrate the effectiveness of pMatch, a library search experiment was conducted on a public dataset with over 40 000 spectra in comparison with SpectraST, the most popular library search engine. Additional validations were done on four published datasets including over 150 000 spectra. The results showed that pMatch can effectively identify unanticipated modifications and significantly increase spectral identification rate. Availability:http://pfind.ict.ac.cn/pmatch/ Contact:yfu@ict.ac.cn; rxsun@ict.ac.cn Supplementary information:Supplementary data are available at Bioinformatics online.
Collapse
Affiliation(s)
- Ding Ye
- Institute of Computing Technology and Key Lab of Intelligent Information Processing, Chinese Academy of Sciences, Beijing 100190, China
| | | | | | | | | | | | | |
Collapse
|
16
|
Nesvizhskii AI. A survey of computational methods and error rate estimation procedures for peptide and protein identification in shotgun proteomics. J Proteomics 2010; 73:2092-123. [PMID: 20816881 DOI: 10.1016/j.jprot.2010.08.009] [Citation(s) in RCA: 358] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2010] [Revised: 08/25/2010] [Accepted: 08/25/2010] [Indexed: 12/18/2022]
Abstract
This manuscript provides a comprehensive review of the peptide and protein identification process using tandem mass spectrometry (MS/MS) data generated in shotgun proteomic experiments. The commonly used methods for assigning peptide sequences to MS/MS spectra are critically discussed and compared, from basic strategies to advanced multi-stage approaches. A particular attention is paid to the problem of false-positive identifications. Existing statistical approaches for assessing the significance of peptide to spectrum matches are surveyed, ranging from single-spectrum approaches such as expectation values to global error rate estimation procedures such as false discovery rates and posterior probabilities. The importance of using auxiliary discriminant information (mass accuracy, peptide separation coordinates, digestion properties, and etc.) is discussed, and advanced computational approaches for joint modeling of multiple sources of information are presented. This review also includes a detailed analysis of the issues affecting the interpretation of data at the protein level, including the amplification of error rates when going from peptide to protein level, and the ambiguities in inferring the identifies of sample proteins in the presence of shared peptides. Commonly used methods for computing protein-level confidence scores are discussed in detail. The review concludes with a discussion of several outstanding computational issues.
Collapse
|