Identification of secretion determinants of the Bordetella pertussis BrkA autotransporter.
The autotransporters comprise a functionally diverse family of gram-negative proteins that mediate their own export across the bacterial outer membrane. They consist of an amino-terminal passenger region called the "alpha-domain" and the structural hallmark of the autotransporter family, a carboxy-terminal transporter region usually referred to as the "beta-domain." The passenger region can be quite diverse and constitutes the effector functions of these proteins, whereas the C-terminal region is conserved and is responsible for translocating the passenger moiety across the outer membrane. BrkA is the 103-kDa autotransporter protein in Bordetella pertussis that is cleaved to yield a 73-kDa N-terminal alpha-domain and a 30-kDa C-terminal beta-domain. We have previously shown that a recombinant form of the beta-domain of BrkA is capable of forming channels in artificial membranes. Here, we define two additional secretion determinants of BrkA. N-terminal sequencing of the 73-kDa BrkA passenger from B. pertussis and Escherichia coli revealed that BrkA has a 42-amino-acid signal peptide. In addition, deletion analysis of BrkA identified a 31- to 39-amino-acid region found immediately upstream of the beta-domain that was essential for surface expression. This 31- to 39-amino-acid linker region, together with the beta-domain, defines the minimal BrkA translocation unit. The linker region may also serve to anchor the BrkA passenger to the bacterial surface.
Oliver
David C
DC
Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada V6T 1Z3.
Huang
George
G
Fernandez
Rachel C
RC
D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001886:Bordetella pertussis / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D021382:Protein Sorting Signals / Q000235:genetics*
D001425:Bacterial Outer Membrane Proteins; C090007:BrkA protein, Bordetella pertussis; D021382:Protein Sorting Signals