title: The Escherichia coli phosphotyrosine proteome relates to core pathways and virulence.
abstract: While phosphotyrosine modification is an established regulatory mechanism in eukaryotes, it is less well characterized in bacteria due to low prevalence. To gain insight into the extent and biological importance of tyrosine phosphorylation in Escherichia coli, we used immunoaffinity-based phosphotyrosine peptide enrichment combined with high resolution mass spectrometry analysis to comprehensively identify tyrosine phosphorylated proteins and accurately map phosphotyrosine sites. We identified a total of 512 unique phosphotyrosine sites on 342 proteins in E. coli K12 and the human pathogen enterohemorrhagic E. coli (EHEC) O157:H7, representing the largest phosphotyrosine proteome reported to date in bacteria. This large number of tyrosine phosphorylation sites allowed us to define five phosphotyrosine site motifs. Tyrosine phosphorylated proteins belong to various functional classes such as metabolism, gene expression and virulence. We demonstrate for the first time that proteins of a type III secretion system (T3SS), required for the attaching and effacing (A/E) lesion phenotype characteristic for intestinal colonization by certain EHEC strains, are tyrosine phosphorylated by bacterial kinases. Yet, A/E lesion and metabolic phenotypes were unaffected by the mutation of the two currently known tyrosine kinases, Etk and Wzc. Substantial residual tyrosine phosphorylation present in an etk wzc double mutant strongly indicated the presence of hitherto unknown tyrosine kinases in E. coli. We assess the functional importance of tyrosine phosphorylation and demonstrate that the phosphorylated tyrosine residue of the regulator SspA positively affects expression and secretion of T3SS proteins and formation of A/E lesions. Altogether, our study reveals that tyrosine phosphorylation in bacteria is more prevalent than previously recognized, and suggests the involvement of phosphotyrosine-mediated signaling in a broad range of cellular functions and virulence.
authors.affiliation: Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America.
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Hansen
authors.forename: Raghothama
authors.initials: R
authors.lastname: Chaerkady
authors.forename: Jyoti
authors.initials: J
authors.lastname: Sharma
authors.forename: J Javier
authors.initials: JJ
authors.lastname: Díaz-Mejía
authors.forename: Nidhi
authors.initials: N
authors.lastname: Tyagi
authors.forename: Santosh
authors.initials: S
authors.lastname: Renuse
authors.forename: Harrys K C
authors.initials: HK
authors.lastname: Jacob
authors.forename: Sneha M
authors.initials: SM
authors.lastname: Pinto
authors.forename: Nandini A
authors.initials: NA
authors.lastname: Sahasrabuddhe
authors.forename: Min-Sik
authors.initials: MS
authors.lastname: Kim
authors.forename: Bernard
authors.initials: B
authors.lastname: Delanghe
authors.forename: Narayanaswamy
authors.initials: N
authors.lastname: Srinivasan
authors.forename: Andrew
authors.initials: A
authors.lastname: Emili
authors.forename: James B
authors.initials: JB
authors.lastname: Kaper
authors.forename: Akhilesh
authors.initials: A
authors.lastname: Pandey
mesh_terms: D054308:Enteropathogenic Escherichia coli / Q000235:genetics / Q000378:metabolism*; D048168:Escherichia coli K12 / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D019000:Phosphotyrosine / Q000235:genetics / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D020543:Proteome / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology
chemical_list: D029968:Escherichia coli Proteins; C120614:Etk protein, E coli; D008565:Membrane Proteins; D020543:Proteome; D019000:Phosphotyrosine; D011505:Protein-Tyrosine Kinases; C499615:wzc protein, E coli