Send to

Choose Destination
Mol Microbiol. 2008 Jan;67(1):188-201. Epub 2007 Nov 27.

Incorporation of a polypeptide segment into the beta-domain pore during the assembly of a bacterial autotransporter.

Author information

Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0538, USA.


Bacterial autotransporters consist of an N-terminal 'passenger domain' that is transported into the extracellular space by an unknown mechanism and a C-terminal 'beta-domain' that forms a beta-barrel in the outer membrane. Recent studies have revealed that fully assembled autotransporters have an unusual architecture in which a small passenger domain segment traverses the pore formed by the beta-domain. It is unclear, however, whether this configuration forms prior to passenger domain translocation or results from the translocation of the passenger domain through the beta-domain pore. By examining the accessibility of tobacco etch virus protease sites and single-cysteine residues in the passenger domain of the Escherichia coli O157:H7 autotransporter EspP at different stages of protein biogenesis, we identified a novel pre-translocation intermediate whose topology resembles that of the fully assembled protein. This intermediate was isolated in the periplasm in cell fractionation experiments. The data strongly suggest that the EspP beta-domain and an embedded polypeptide segment are integrated into the outer membrane as a single pre-formed unit. The data also provide indirect evidence that at least some outer membrane proteins acquire considerable tertiary structure prior to their membrane integration.

[Indexed for MEDLINE]
Free full text

Supplemental Content

Full text links

Icon for Wiley
Loading ...
Support Center