Salmonella Research Today is a free monthly online journal that collates and summarizes the latest research about Salmonella, including details on salmonella typhimurium, food poisoning, infection, treatment.

Salmonella enterica serotype Typhimurium MisL is an intestinal colonization factor that binds fibronectin.

Dorsey CW, Laarakker MC, Humphries AD, Weening EH, Bäumler AJ

Department of Medical Microbiology and Immunology, College of Medicine, Texas A&M University System Health Science Center, 407 Reynolds Medical Building, College Station, TX 77843-1114, USA.

MisL is an autotransporter protein encoded by Salmonella pathogenicity island 3 (SPI3). To investigate the role of MisL in Salmonella enterica serotype Typhimurium (S. Typhimurium) pathogenesis, we characterized its function during infection of mice and identified a host receptor for this adhesin. In a mouse model of S. Typhimurium intestinal persistence, a misL mutant was shed with the faeces in significantly lower numbers than the wild type and was impaired in its ability to colonize the cecum. Previous studies have implicated binding of extracellular matrix proteins as a possible mechanism for S. Typhimurium intestinal persistence. A gluthathione-S-transferase (GST) fusion protein to the MisL passenger domain (GST-MisL(29-281)) was constructed to investigate binding to extracellular matrix proteins. In a solid-phase binding assay the purified GST-MisL(29-281) fusion protein bound to fibronectin and collagen IV, but not to collagen I. MisL expression was not detected by Western blot in S. Typhimurium grown under standard laboratory conditions. However, when expression of the cloned misL gene was driven by the Escherichia coli arabinose promoter, MisL could be detected in the S. Typhimurium outer membrane by Western blot and on the bacterial cell surface by flow cytometry. Expression of MisL enabled S. Typhimurium to bind fibronectin to its cell surface, resulting in attachment to fibronectin-coated glass slides and in increased invasiveness for human epithelial cells derived from colonic carcinoma (T84 cells). These data identify MisL as an extracellular matrix adhesin involved in intestinal colonization.

Published 13 June 2005 in Mol Microbiol, 57(1): 196-211.
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