Grant: Project Grant

Bacteria have evolved sophisticated assemblies to passage macromolecules essential to subsequent disease across their lipid membrane barriers. The Type III Secretion system "injectisome" is one prominent example, a syringe like complex that is essential for downstream pathogenesis of many health related bacterial species in the clinic and community. This includes the causative agents of food and water borne disease, plague, hospital acquired infections, sexually transmitted disease and beyond. A remarkably sophisticated complex of two dozen highly oligomerized proteins spanning the 2 membranes of the bacteria as well as that of the human host cells they infect, the Strynadka laboratory has been a leader in the structure-guided study of the molecular underpinnings of how the injectisome works. Here her laboratory proposes to use a combination of sophisticated biophysical tools including xray crystallography and cryogenic electron microscopy (single particle/tomography) supported by cellular microbiology to study the atomic features and function of the injectisome in isolation and within the native context of the bacterial cells whose pathogenicity they promote. A related but distinct nanomachine, with many analogies to the Type III injectisome, is the "feeding tube" apparatus Clostridioides difficile mother cells use to passage essential molecules to the daugter cell, the latter which is destined to become a robust long-lived spore that allows this notorious hospital acquired pathogen to persist under even the harshest sanitization methods. The Strynadka laboratory propose to use a similar toolbox of biophysical and microbiology methods to study this fascinating system in vitro and in situ within C.difficile cells. Atomic information gleaned from these studies will drive essential understanding of how molecules are passaged across multiple membranes, and sets the foundation for design of antimicrobials to block their action and subsequent disease causing effects.