Conformational changes in IpaD from Shigella flexneri upon binding bile salts provide insight into the second step of type III secretion.

ABSTRACT: Shigella flexneri uses its type III secretion apparatus (TTSA) to inject host-altering proteins into targeted eukaryotic cells. The TTSA is composed of a basal body and an exposed needle with invasion plasmid antigen D (IpaD) forming a tip complex that controls secretion. The bile salt deoxycholate (DOC) stimulates recruitment of the translocator protein IpaB into the maturing TTSA needle tip complex. This process appears to be triggered by a direct interaction between DOC and IpaD. Fluorescence spectroscopy and NMR spectroscopy are used here to confirm the DOC-IpaD interaction and to reveal that IpaD conformational changes upon DOC binding trigger the appearance of IpaB at the needle tip. Förster resonance energy transfer between specific sites on IpaD was used here to identify changes in

SUBMITTER: Dickenson NE 

PROVIDER: S-EPMC3130115 | biostudies-literature | 2011 Jan

REPOSITORIES: biostudies-literature