title: pIV, a filamentous phage protein that mediates phage export across the bacterial cell envelope, forms a multimer.
abstract: Filamentous phage pIV is an outer membrane protein required for phage assembly and secretion. Chemical cross-linking and sedimentation experiments have been used to demonstrate that pIV from f1-infected Escherichia coli exists as a homo-multimer, probably composed of 10 to 12 subunits. pIV secreted from spheroplasts remains soluble and does not form multimers. Synthesis of pIV from distantly related filamentous phages or from a bacterial homolog that participates in a specialized form of extra-cellular protein secretion in the same cell with pIVf1 resulted in the formation of mixed multimers. This suggests that the homologous proteins themselves form homo-multimers. These structures could form gated channels that conduct assembling phage or specific substrate proteins across the outer membrane to the extracellular milieu.
authors.affiliation: Rockefeller University, New York, NY 10021.
authors.forename: B I
authors.initials: BI
authors.lastname: Kazmierczak
authors.forename: D L
authors.initials: DL
authors.lastname: Mielke
authors.forename: M
authors.initials: M
authors.lastname: Russel
authors.forename: P
authors.initials: P
authors.lastname: Model
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D001704:Biopolymers; D002499:Centrifugation, Density Gradient; D003090:Coliphages / Q000737:chemistry*; D003432:Cross-Linking Reagents; D016974:Dickeya chrysanthemi / Q000737:chemistry; D004926:Escherichia coli / Q000378:metabolism; D017912:Inovirus / Q000737:chemistry; D011233:Precipitin Tests; D013104:Spheroplasts / Q000378:metabolism; D014764:Viral Proteins / Q000737:chemistry* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D001704:Biopolymers; D003432:Cross-Linking Reagents; D014764:Viral Proteins