title: Assembly of the secretion pores GspD, Wza and CsgG into bacterial outer membranes does not require the Omp85 proteins BamA or TamA.
abstract: In Gram-negative bacteria, β-barrel proteins are integrated into the outer membrane by the β-barrel assembly machinery, with key components of the machinery being the Omp85 family members BamA and TamA. Recent crystal structures and cryo-electron microscopy show a diverse set of secretion pores in Gram-negative bacteria, with α-helix (Wza and GspD) or β-strand (CsgG) transmembrane segments in the outer membrane. We developed assays to measure the assembly of three distinct secretion pores that mediate protein (GspD), curli fibre (CsgG) and capsular polysaccharide (Wza) secretion by bacteria and show that depletion of BamA and TamA does not diminish the assembly of Wza, GspD or CsgG. Like the well characterised pilotins for GspD and other secretins, small periplasmic proteins enhance the assembly of the CsgG β-barrel. We discuss a model for integral protein assembly into the bacterial outer membrane, focusing on the commonalities and differences in the assembly of Wza, GspD and CsgG.
authors.affiliation: Department of Microbiology, Monash University, Clayton, Vic., 3800, Australia.|Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic., 3800, Australia.
authors.forename: Rhys A
authors.initials: RA
authors.lastname: Dunstan
authors.affiliation: Department of Microbiology, Monash University, Clayton, Vic., 3800, Australia.
authors.forename: Iain D
authors.initials: ID
authors.lastname: Hay
authors.affiliation: Department of Microbiology & Immunology, The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville, Vic., 3052, Australia.
authors.forename: Jonathan J
authors.initials: JJ
authors.lastname: Wilksch
authors.affiliation: Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic., 3800, Australia.
authors.forename: Ralf B
authors.initials: RB
authors.lastname: Schittenhelm
authors.affiliation: Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic., 3800, Australia.
authors.forename: Anthony W
authors.initials: AW
authors.lastname: Purcell
authors.affiliation: Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic., 3800, Australia.
authors.forename: Joan
authors.initials: J
authors.lastname: Clark
authors.affiliation: Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic., 3800, Australia.
authors.forename: Adam
authors.initials: A
authors.lastname: Costin
authors.affiliation: Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic., 3800, Australia.
authors.forename: Georg
authors.initials: G
authors.lastname: Ramm
authors.affiliation: Department of Microbiology & Immunology, The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville, Vic., 3052, Australia.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Strugnell
authors.affiliation: Department of Microbiology, Monash University, Clayton, Vic., 3800, Australia.
authors.forename: Trevor
authors.initials: T
authors.lastname: Lithgow
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D058947:Bacterial Secretion Systems / Q000378:metabolism; D020285:Cryoelectron Microscopy; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006090:Gram-Negative Bacteria / Q000235:genetics / Q000378:metabolism*; D008074:Lipoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D018272:Porins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017433:Protein Structure, Secondary
chemical_list: D001425:Bacterial Outer Membrane Proteins; D058947:Bacterial Secretion Systems; C503914:BamA protein, E coli; C534546:CsgG protein, E coli; D029968:Escherichia coli Proteins; C540076:GspD protein, E coli; D008074:Lipoproteins; D018272:Porins; C404158:Wza protein, E coli