Outside-in or inside-out: Analyzing the assembly pathway of the type III secretion injectisome of Salmonella

Abstract

With the aim to reveal the assembly pathway of Salmonella Typhimurium T3SS, we used in vivo photocrosslinking to test interactions between different proteins in various genetic backgrounds with a focus on components of the base and export apparatus. Based on the results, we propose a model in which assembly is carried out from two nucleation points. Assembly starts simultaneously at the outer membrane with the secretin and at the inner membrane with the export apparatus, onto which PrgK (SctJ) assembles. Initially, di- and trimers of PrgH (SctD) are attached to the secretin, but they can only form their complete ring in the presence of the export apparatus - PrgK intermediate; PrgK seems to be necessary as a template for the oligomerization of PrgH. A decision in favor of inside-out or outside-in assembly is therefore not possible.

Die Dissertation ist gesperrt bis zum 31. März 2027 !