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.

SUBMITTER: Al-Hasani K 

PROVIDER: S-EPMC97446 | biostudies-literature | 2000 May

REPOSITORIES: biostudies-literature