title: The sigA gene which is borne on the she pathogenicity island of Shigella flexneri 2a encodes an exported cytopathic protease involved in intestinal fluid accumulation.
abstract: In this study, the sigA gene situated on the she pathogenicity island of Shigella flexneri 2a was cloned and characterized. Sequence analysis showed that sigA encodes a 139.6-kDa protein which belongs to the SPATE (serine protease autotransporters of Enterobacteriaceae) subfamily of autotransporter proteins. The demonstration that SigA is autonomously secreted from the cell to yield a 103-kDa processed form and possesses a conserved C-terminal domain for export from the cell were consistent with the autotransporter pathway of secretion. Functional analysis showed that SigA is a secreted temperature-regulated serine protease capable of degrading casein. SigA was cytopathic for HEp-2 cells, suggesting that it may be a cell-altering toxin with a role in the pathogenesis of Shigella infections. SigA was at least partly responsible for the ability of S. flexneri to stimulate fluid accumulation in ligated rabbit ileal loops.
authors.affiliation: Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia.
authors.forename: K
authors.initials: K
authors.lastname: Al-Hasani
authors.forename: I R
authors.initials: IR
authors.lastname: Henderson
authors.forename: H
authors.initials: H
authors.lastname: Sakellaris
authors.forename: K
authors.initials: K
authors.lastname: Rajakumar
authors.forename: T
authors.initials: T
authors.lastname: Grant
authors.forename: J P
authors.initials: JP
authors.lastname: Nataro
authors.forename: R
authors.initials: R
authors.lastname: Robins-Browne
authors.forename: B
authors.initials: B
authors.lastname: Adler
mesh_terms: D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004269:DNA, Bacterial; D004405:Dysentery, Bacillary / Q000503:physiopathology*; D004926:Escherichia coli; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D006801:Humans; D007082:Ileum / Q000382:microbiology / Q000503:physiopathology; D008969:Molecular Sequence Data; D011817:Rabbits; D017422:Sequence Analysis, DNA; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D012763:Shigella flexneri / Q000201:enzymology* / Q000472:pathogenicity; D013696:Temperature; D014407:Tumor Cells, Cultured
chemical_list: D004269:DNA, Bacterial; D012697:Serine Endopeptidases; C021433:IgA-specific serine endopeptidase