The periplasmic enzyme, AnsB, of Shigella flexneri modulates bacterial adherence to host epithelial cells.
S. flexneri strains, most frequently linked with endemic outbreaks of shigellosis, invade the colonic and rectal epithelium of their host and cause severe tissue damage. Here we have attempted to elucidate the contribution of the periplasmic enzyme, L-asparaginase (AnsB) to the pathogenesis of S. flexneri. Using a reverse genetic approach we found that ansB mutants showed reduced adherence to epithelial cells in vitro and attenuation in two in vivo models of shigellosis, the Caenorhabditis elegans and the murine pulmonary model. To investigate how AnsB affects bacterial adherence, we compared the proteomes of the ansB mutant with its wild type parental strain using two dimensional differential in-gel electrophoresis and identified the outer membrane protein, OmpA as up-regulated in ansB mutant cells. Bacterial OmpA, is a prominent outer membrane protein whose activity has been found to be required for bacterial pathogenesis. Overexpression of OmpA in wild type S. flexneri serotype 3b resulted in decreasing the adherence of this virulent strain, suggesting that the up-regulation of OmpA in ansB mutants contributes to the reduced adherence of this mutant strain. The data presented here is the first report that links the metabolic enzyme AnsB to S. flexneri pathogenesis.
Division of Biomedical Science and Biochemistry, Research School of Biology, The Australian National University, Canberra, Australia.
Divya T
DT
George
Division of Plant Science, Research School of Biology, The Australian National University, Canberra, Australia.
Ulrike
U
Mathesius
Division of Biomedical Science and Biochemistry, Research School of Biology, The Australian National University, Canberra, Australia.
Carolyn A
CA
Behm
Division of Biomedical Science and Biochemistry, Research School of Biology, The Australian National University, Canberra, Australia.
Naresh K
NK
Verma
D000818:Animals; D001215:Asparaginase / Q000737:chemistry / Q000502:physiology*; D001216:Asparagine / Q000737:chemistry; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000737:chemistry / Q000502:physiology*; D017173:Caenorhabditis elegans; D002460:Cell Line; D006224:Cricetinae; D004405:Dysentery, Bacillary / Q000382:microbiology*; D004847:Epithelial Cells / Q000382:microbiology*; D005260:Female; D015870:Gene Expression; D015964:Gene Expression Regulation, Bacterial; D054884:Host-Pathogen Interactions; D006868:Hydrolysis; D008807:Mice, Inbred BALB C; D033903:Periplasmic Proteins / Q000737:chemistry / Q000502:physiology*; D012763:Shigella flexneri / Q000201:enzymology* / Q000254:growth & development
D001426:Bacterial Proteins; D033903:Periplasmic Proteins; D001216:Asparagine; D001215:Asparaginase