Maintenance of an unfolded polypeptide by a cognate chaperone in bacterial type III secretion

摘要: Many bacterial pathogens use a type III protein secretion system to deliver virulence effector proteins directly into the host cell cytosol, where they modulate cellular processes1,2. A requirement for effective translocation of several such is binding specific cytosolic chaperones, which typically interact with discrete domains in factors3,4,5. We report here crystal structure at 1.9 A resolution chaperone-binding domain Salmonella SptP its cognate chaperone SicP. The reveals that this maintained an extended, unfolded conformation wound around three successive molecules. Short segments from two different molecules are juxtaposed by dimerize across hydrophobic interface. These results imply chaperones associated maintain their substrates secretion-competent state capable engaging machinery travel through apparatus or partially folded manner.