An inner membrane platform in the type II secretion machinery of Gram-negative bacteria.
The type II secretion machinery allows most Gram-negative bacteria to deliver virulence factors into their surroundings. We report that in Erwinia chrysanthemi, GspE (the putative NTPase), GspF, GspL and GspM constitute a complex in the inner membrane that is presumably used as a platform for assembling other parts of the secretion machinery. The GspE-GspF-GspL-GspM complex was demonstrated by two methods: (i) co-immunoprecipitation of GspE-GspF-GspL with antibodies raised against either GspE or GspF; (ii) interactions in the yeast two-hybrid system between GspF and GspE, GspF and GspL, GspL and GspM. GspL was found to have an essential role in complex formation. We propose a model in which the GspE-GspF-GspL-GspM proteins constitute a building block within the secretion machinery on top of which another building block, referred to as a pseudopilus, assembles. By analogy, we predict that a similar platform is required for the biogenesis of the type IV pilus.
Laboratoire de Chimie Bactérienne, IBSM, CNRS, 31 chemin Joseph Aiguier, Marseille Cedex 20, 13402, France. py@ibsm.cnrs-mrs.fr
B
B
Py
L
L
Loiseau
F
F
Barras
D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D016974:Dickeya chrysanthemi / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity; D006090:Gram-Negative Bacteria / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D008954:Models, Biological; D028044:Phosphate-Binding Proteins; D020798:Two-Hybrid System Techniques; D014774:Virulence
D001425:Bacterial Outer Membrane Proteins; D002352:Carrier Proteins; C120189:OutE protein, Erwinia chrysanthemi; C105758:OutF protein, Pectobacterium carotovorum; D028044:Phosphate-Binding Proteins