Actin Based Motility
Actin based motility (ABM) is used by a number of microbial pathogens to move inside and between infected host (animal and human) cells. In Shigella flexneri, the outer membrane IcsA protein is reponsible for nucleating actin polymerisation by subverting host cell actin and actin regulatory proteins (e.g. N-WASP, Arp2/3 complex, Profilin, Cofilin, CapZ).
ABM can be visualized by staining using FITC-phalloidin to detect the F-actin comet tails that are formed. Additionally, time-lapse video microscopy can be used to visualise and measure the rate of motility.
In addition to IcsA, bacterial factors such as lipopolysaccharides also impact on IcsA function and intercellular spreading.
Morona, R., and Van Den Bosch, L. (2003) "Lipopolysaccharide O antigen chains mask IcsA(VirG) in Shigella flexneri" FEMS Microbiol. Lett. 221: 173-180.
Morona, R., and Van Den Bosch, L. (2003) "Multi-copy icsA is able to suppress the virulence defect caused by the wzzSF mutation in Shigella flexneri." FEMS Microbiol. Lett. 221: 213-219.
Van Den Bosch, L. and Morona, R. (2003) "The actin-based motility defect of Shigella flexneri rmlD rough LPS mutant is not due to loss of IcsA polarity." Microb. Pathogen. 35: 11-18.
Van Den Bosch, L., Manning, P.A., and Morona, R. (1997) “Regulation of O-antigen chain length is required for Shigella flexneri virulence”. Mol. Microbiol. 23: 765-775