We analyzed HeLa cells proteome in response to Salmonella ubiquitin ligase SlrP.
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Significant differential expression was detected for 37 human proteins.
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The level of corresponding mRNAs was altered for only a fraction of these proteins.
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Cell adhesion and cell migration were altered in SlrP-expressing cells.
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These results could be a guide for future research on SlrP substrates.
Abstract
The virulence of the human and animal pathogen Salmonella enterica serovar Typhimurium is dependent on two type III secretion systems. These systems translocate proteins called effectors into eukaryotic host cells. SlrP is a Salmonella type III secretion effector with ubiquitin ligase activity. Here, we used two complementary proteomic approaches, two-dimensional gel electrophoresis and iTRAQ (isobaric tags for relative and absolute quantification) to study the consequences of the presence of SlrP in human epithelial cells. We identified 37 proteins that were differentially expressed in HeLa cells expressing slrP compared to control cells. Microarray analysis revealed that more than a half of differentially expressed proteins did not show changes in the transcriptome, suggesting post-transcriptional regulation. A gene ontology overrepresentation test carried out on the differentially expressed proteins revealed enrichment of ontology terms related to several types of junctions mediating adhesion in epithelial cells. Consistently, slrP-transfected cells showed defects in migration and adhesion. Our results suggest that the modification of cell–cell interaction ability of the host could be one of the final consequences of the action of SlrP during an infection.
Graphical abstract
Keywords
SlrP
Salmonella
Type III secretion
iTRAQ
Cell adhesion
Abbreviations
T3SS
type three secretion system
SPI
Salmonella pathogenicity island
SCV
Salmonella-containing vacuole
iTRAQ
isobaric tags for relative and absolute quantification