title: Unprecedented Abundance of Protein Tyrosine Phosphorylation Modulates Shigella flexneri Virulence.
abstract: Evidence is accumulating that protein tyrosine phosphorylation plays a crucial role in the ability of important human bacterial pathogens to cause disease. While most works have concentrated on its role in the regulation of a major bacterial virulence factor, the polysaccharide capsule, recent studies have suggested a much broader role for this post-translational modification. This prompted us to investigate protein tyrosine phosphorylation in the human pathogen Shigella flexneri. We first completed a tyrosine phosphoproteome, identifying 905 unique tyrosine phosphorylation sites on at least 573 proteins (approximately 15% of all proteins). This is the most tyrosine-phosphorylated sites and proteins in a single bacterium identified to date, substantially more than the level seen in eukaryotic cells. Most had not previously been identified and included proteins encoded by the virulence plasmid, which is essential for S. flexneri to invade cells and cause disease. In order to investigate the function of these phosphorylation sites in important virulence factors, phosphomimetic and ablative mutations were constructed in the type 3 secretion system ATPase Spa47 and the master virulence regulator VirB. This revealed that tyrosine residues phosphorylated in our study are critical for Spa47 and VirB activity, and tyrosine phosphorylation likely regulates their functional activity and subsequently the virulence of this major human pathogen. This study suggests that tyrosine phosphorylation plays a critical role in regulating a wide variety of virulence factors in the human pathogen S. flexneri and serves as a base for future studies defining its complete role.
authors.affiliation: Research Centre for Infectious Diseases, Department of Molecular and Cellular Biology, School of Biological Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia. Electronic address: alistair.standish@adelaide.edu.au.
authors.forename: Alistair James
authors.initials: AJ
authors.lastname: Standish
authors.affiliation: Research Centre for Infectious Diseases, Department of Molecular and Cellular Biology, School of Biological Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia.
authors.forename: Min Yan
authors.initials: MY
authors.lastname: Teh
authors.affiliation: Research Centre for Infectious Diseases, Department of Molecular and Cellular Biology, School of Biological Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia.
authors.forename: Elizabeth Ngoc Hoa
authors.initials: ENH
authors.lastname: Tran
authors.affiliation: Research Centre for Infectious Diseases, Department of Molecular and Cellular Biology, School of Biological Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia.
authors.forename: Matthew Thomas
authors.initials: MT
authors.lastname: Doyle
authors.affiliation: Research Centre for Infectious Diseases, Department of Molecular and Cellular Biology, School of Biological Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Baker
authors.affiliation: Research Centre for Infectious Diseases, Department of Molecular and Cellular Biology, School of Biological Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia.
authors.forename: Renato
authors.initials: R
authors.lastname: Morona
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D006367:HeLa Cells; D006801:Humans; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D020543:Proteome / Q000032:analysis; D012763:Shigella flexneri / Q000378:metabolism* / Q000472:pathogenicity*; D014443:Tyrosine / Q000378:metabolism*; D014774:Virulence
chemical_list: D001426:Bacterial Proteins; D020543:Proteome; D014443:Tyrosine
keywords: Spa47; VirB; post-translational modification; type 3 secretion system; virulence regulation