Reconstitution of bacterial autotransporter assembly using purified components.

ABSTRACT: Autotransporters are a superfamily of bacterial virulence factors consisting of an N-terminal extracellular ('passenger') domain and a C-terminal ? barrel ('?') domain that resides in the outer membrane (OM). The mechanism by which the passenger domain is secreted is poorly understood. Here we show that a conserved OM protein insertase (the Bam complex) and a molecular chaperone (SurA) are both necessary and sufficient to promote the complete assembly of the Escherichia coli O157:H7 autotransporter EspP in vitro. Our results indicate that the membrane integration of the ? domain is the rate-limiting step in autotransporter assembly and that passenger domain translocation does not require the input of external energy. Furthermore, experiments using nanodiscs strongly suggest that autotransporter assembly is catalyzed by a single copy of the Bam complex. Finally, we describe a method to purify a highly active form of the Bam complex that should facilitate the elucidation of its function.

SUBMITTER: Roman-Hernandez G 

PROVIDER: S-EPMC4174580 | biostudies-literature | 2014 Sep

REPOSITORIES: biostudies-literature