The Bam (Omp85) complex is involved in secretion of the autotransporter haemoglobin protease.
Autotransporters are large virulence factors secreted by Gram-negative bacteria. They are synthesized with a C-terminal domain that forms a beta-barrel pore in the outer membrane implicated in translocation of the upstream 'passenger' domain across the outer membrane. However, recent structural data suggest that the diameter of the beta-barrel pore is not sufficient to allow the passage of partly folded structures observed for several autotransporters. Here, we have used a stalled translocation intermediate of the autotransporter Hbp to identify components involved in insertion and translocation of the protein across the outer membrane. At this intermediate stage the beta-domain was not inserted and folded as an integral beta-barrel in the outer membrane whereas part of the passenger was surface exposed. The intermediate was copurified with the periplasmic chaperone SurA and subunits of the Bam (Omp85) complex that catalyse the insertion and assembly of outer-membrane proteins. The data suggest a critical role for this general machinery in the translocation of autotransporters across the outer membrane.
Sauri
Ana
A
Department of Molecular Microbiology, Institute of Molecular Cell Biology, VU University, 1081 HV Amsterdam, The Netherlands.
Soprova
Zora
Z
Department of Molecular Microbiology, Institute of Molecular Cell Biology, VU University, 1081 HV Amsterdam, The Netherlands.
Wickström
David
D
Center for Biomembrane Research, Department of Biochemistry and Biophysics, Arrhenius Laboratories, Stockholm University, SE-106 91 Stockholm, Sweden.
de Gier
Jan-Willem
JW
Center for Biomembrane Research, Department of Biochemistry and Biophysics, Arrhenius Laboratories, Stockholm University, SE-106 91 Stockholm, Sweden.
Van der Schors
Roel C
RC
Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, VU University, 1081 HV Amsterdam, The Netherlands.
Smit
August B
AB
Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, VU University, 1081 HV Amsterdam, The Netherlands.
Jong
Wouter S P
WSP
Department of Molecular Microbiology, Institute of Molecular Cell Biology, VU University, 1081 HV Amsterdam, The Netherlands.
Luirink
Joen
J
Department of Molecular Microbiology, Institute of Molecular Cell Biology, VU University, 1081 HV Amsterdam, The Netherlands.
D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001693:Biological Transport, Active; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D003545:Cysteine / Q000737:chemistry; D010450:Endopeptidases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005798:Genes, Bacterial; D008954:Models, Biological; D008958:Models, Molecular; D046912:Multiprotein Complexes; D016297:Mutagenesis, Site-Directed; D019696:Peptidylprolyl Isomerase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D037521:Virulence Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D001425:Bacterial Outer Membrane Proteins; C503914:BamA protein, E coli; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; D046912:Multiprotein Complexes; D011994:Recombinant Proteins; D037521:Virulence Factors; D010450:Endopeptidases; C114676:hemoglobin protease Hbp; C490900:SurA protein, E coli; D019696:Peptidylprolyl Isomerase; D003545:Cysteine