Dataset Information

Characterization of peptide-protein relationships in protein ambiguity groups via bipartite graphs - data set D3 (without and with isoforms)

ABSTRACT: Motivation: In bottom-up mass spectrometry proteins are enzymatically digested before measurement. The relationship between proteins and peptides can be represented by bipartite graphs that can be split into connected components. This representation is useful to aid protein inference and quantification, which is complex due to the occurrence of shared peptides. We conducted a comprehensive analysis of these bipartite graphs using peptides from an in silico digestion of protein databases as well as quantified peptides. Results: The graphs based on quantified peptides are smaller and have less complex structures compared to the database level. However, the proportion of protein nodes without unique peptides and the proportion of graphs that contain these proteins increase. Large differences between the different underlying organisms on database as well as quantitative level could be observed. Insights of this analysis may be useful for the development of protein inference and quantification algorithms. Link to preprint: https://www.biorxiv.org/content/10.1101/2021.07.28.454128v1?ct=

INSTRUMENT(S): LTQ Orbitrap

ORGANISM(S): Homo Sapiens (human) Escherichia Coli

TISSUE(S): Cell Culture

SUBMITTER: Karin Schork

LAB HEAD: Martin Eisenacher

PROVIDER: PXD030603 | Pride | 2022-11-11

REPOSITORIES: Pride

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Publications

Characterization of peptide-protein relationships in protein ambiguity groups via bipartite graphs.

Schork Karin K Turewicz Michael M Uszkoreit Julian J Rahnenführer Jörg J Eisenacher Martin M

PloS one 20221021 10

In bottom-up proteomics, proteins are enzymatically digested into peptides before measurement with mass spectrometry. The relationship between proteins and their corresponding peptides can be represented by bipartite graphs. We conduct a comprehensive analysis of bipartite graphs using quantified peptides from measured data sets as well as theoretical peptides from an in silico digestion of the corresponding complete taxonomic protein sequence databases. The aim of this study is to characterize ...[more]

PMID: 36269744

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Project description:Escherichia coliÂ spans a genetic continuum from enteric strains to several phylogenetically distinct, atypical lineages that are rare in humans, but more common in extra-intestinal environments. To investigate the link between gene regulation, phylogeny and diversification in this species, we analyzed global gene expression profiles of four strains representing distinct evolutionary lineages, including a well-studied laboratory strain, a typical commensal (enteric) strain and two environmental strains. RNA-Seq was employed to compare the whole transcriptomes of strains grown under batch, chemostat and starvation conditions. Highly differentially expressed genes showed a significantly lower nucleotide sequence identity compared with other genes, indicating that gene regulation and coding sequence conservation are directly connected. Overall, distances between the strains based on gene expression profiles were largely dependent on the culture condition and did not reflect phylogenetic relatedness. Expression differences of commonly shared genes (all four strains) andÂ E. coliÂ core genes were consistently smaller between strains characterized by more similar primary habitats. For instance, environmental strains exhibited increased expression of stress defense genes under carbon-limited growth and entered a more pronounced survival-like phenotype during starvation compared with other strains, which stayed more alert for substrate scavenging and catabolism during no-growth conditions. Since those environmental strains show similar genetic distance to each other and to the other two strains, these findings cannot be simply attributed to genetic relatedness but suggest physiological adaptations. Our study provides new insights into ecologically relevant gene-expression and underscores the role of (differential) gene regulation for the diversification of the model bacterial species. Four E.coli strains, laboratory strain K12 (MG1655), a commensal model strain (IAI1), a soil-isolated strain (TW11588-Clade IV), and a freshwater-isolated strain (TW09308âClade V) were used. Each strain was grown on a minimal growth medium (Ihssen and Egli, 2004) in three treatment modes: chemostat, batch, and starvation. Cells from batch culture were collected when reaching steady-state. For starvation, the medium flow was stopped during steady-state and bacteria were collected after 4âh.

Dataset Information

Characterization of peptide-protein relationships in protein ambiguity groups via bipartite graphs - data set D3 (without and with isoforms)

Publications

Characterization of peptide-protein relationships in protein ambiguity groups via bipartite graphs.

Similar Datasets

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