CHARACTERIZATION OF INVASION PLASMID ANTIGEN B AND C (IpaB AND IpaC) TRANSLOCATOR COMPLEXES AND TRANSLOCATOR/CHAPERONE COMPLEXES OF Shigella flexneri

Abstract

Shigellosis, a severe form of bacillary dysentery, is primarily caused by the gram negative pathogen, Shigella flexneri. In order to elicit disease, the pathogen must pass through the digestive tract and induce its uptake by colonic epithelial cells. To facilitate this process, S. flexneri uses a type III secretion system (TTSS) to form a pore in host cell membranes and deliver translocator and effector proteins to the targeted host cells. Translocon pore formation is the responsibility of the invasion plasmid antigens IpaB and IpaC. Prior to their secretion, IpaB and IpaC are stored in the bacterial cytoplasm where they individually associate with the molecular chaperone IpgC. In this study, a variety of biophysical and molecular techniques were utilized to investigate the structural and functional characteristics of these proteins and the interactions of the translocator/chaperone and the translocator/translocator complexes.