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Proc Natl Acad Sci U S A. 2011 Aug 2;108(31):E383-91. doi: 10.1073/pnas.1103827108. Epub 2011 Jun 6.

Sequential and spatially restricted interactions of assembly factors with an autotransporter beta domain.

Author information

1
Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.

Abstract

Autotransporters are bacterial virulence factors that consist of an N-terminal extracellular ("passenger") domain and a C-terminal β barrel domain ("β domain") that resides in the outer membrane. Here we used an in vivo site-specific photocrosslinking approach to gain insight into the mechanism by which the β domain is integrated into the outer membrane and the relationship between β domain assembly and passenger domain secretion. We found that periplasmic chaperones and specific components of the β barrel assembly machinery (Bam) complex interact with the β domain of the Escherichia coli O157:H7 autotransporter extracellular serine protease P (EspP) in a temporally and spatially regulated fashion. Although the chaperone Skp initially interacted with the entire β domain, BamA, BamB, and BamD subsequently interacted with discrete β domain regions. BamB and BamD remained bound to the β domain longer than BamA and therefore appeared to function at a later stage of assembly. Interestingly, we obtained evidence that the completion of β domain assembly is regulated by an intrinsic checkpoint mechanism that requires the completion of passenger domain secretion. In addition to leading to a detailed model of autotransporter biogenesis, our results suggest that the lipoprotein components of the Bam complex play a direct role in the membrane integration of β barrel proteins.

PMID:
21646511
PMCID:
PMC3150907
DOI:
10.1073/pnas.1103827108
[Indexed for MEDLINE]
Free PMC Article

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