Limited tolerance towards folded elements during secretion of the autotransporter Hbp.
Mol Microbiol
; 63(5): 1524-36, 2007 Mar.
Article
em En
| MEDLINE
| ID: mdl-17302825
ABSTRACT
Many virulence factors secreted by pathogenic Gram-negative bacteria belong to the autotransporter (AT) family. ATs consist of a passenger domain, which is the actual secreted moiety, and a beta-domain that facilitates the transfer of the passenger domain across the outer membrane. Here, we analysed folding and translocation of the AT passenger, using Escherichia coli haemoglobin protease (Hbp) as a model protein. Dual cysteine mutagenesis, instigated by the unique crystal structure of the Hbp passenger, resulted in intramolecular disulphide bond formation dependent on the periplasmic enzyme DsbA. A small loop tied off by a disulphide bond did not interfere with secretion of Hbp. In contrast, a bond between different domains of the Hbp passenger completely blocked secretion resulting in degradation by the periplasmic protease DegP. In the absence of DegP, a translocation intermediate accumulated in the outer membrane. A similar jammed intermediate was formed upon insertion of a calmodulin folding moiety into Hbp. The data suggest that Hbp can fold in the periplasm but must retain a certain degree of flexibility and/or modest width to allow translocation across the outer membrane.
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Base de dados:
MEDLINE
Assunto principal:
Endopeptidases
/
Dobramento de Proteína
/
Proteínas de Escherichia coli
/
Escherichia coli
Tipo de estudo:
Prognostic_studies
Idioma:
En
Ano de publicação:
2007
Tipo de documento:
Article