title: Morphogenetic expression of Moraxella bovis fimbriae (pili) in Pseudomonas aeruginosa.
abstract: Type 4 fimbriae (pili) are found in a wide variety of gram-negative bacteria and are composed of small structural subunits which share significant sequence homology among different species, especially at their amino-terminal ends. Previous studies demonstrating morphogenetic expression of Bacteroides nodosus fimbriae from cloned subunit genes in Pseudomonas aeruginosa suggested that there is a common mechanism for type 4 fimbriae assembly and that the structural subunits are interchangeable (J. S. Mattick et al., J. Bacteriol. 169:33-41, 1987). Here we have examined the expression of Moraxella bovis fimbrial subunits in P. aeruginosa. M. bovis subunits were assembled into extracellular fimbriae in this host, in some cases as a homopolymer but in others as a mosaic with the indigenous subunit, indicating structural equivalence. This result contrasts with other studies in which recombinant P. aeruginosa expressing different subunits produced fimbriae composed almost exclusively of one subunit or the other (T. C. Elleman and J. E. Peterson, Mol. Microbiol. 1:377-380, 1987). Both observations can be explained by reversibility of subunit-subunit interactions at the site of assembly, with the forward equilibrium favoring chain extension between compatible subunits.
authors.affiliation: Department of Animal Health, University of Sydney, Camden, New South Wales, Australia.
authors.forename: M K
authors.initials: MK
authors.lastname: Beard
authors.forename: J S
authors.initials: JS
authors.lastname: Mattick
authors.forename: L J
authors.initials: LJ
authors.lastname: Moore
authors.forename: M R
authors.initials: MR
authors.lastname: Mott
authors.forename: C F
authors.initials: CF
authors.lastname: Marrs
authors.forename: J R
authors.initials: JR
authors.lastname: Egerton
mesh_terms: D004274:DNA, Recombinant / Q000378:metabolism; D010861:Fimbriae, Bacterial / Q000502:physiology* / Q000648:ultrastructure; D005798:Genes, Bacterial; D046911:Macromolecular Substances; D008854:Microscopy, Electron; D009016:Moraxella / Q000235:genetics* / Q000502:physiology / Q000648:ultrastructure; D009024:Morphogenesis; D010957:Plasmids; D011401:Promoter Regions, Genetic; D011550:Pseudomonas aeruginosa / Q000235:genetics* / Q000502:physiology / Q000648:ultrastructure; D015183:Restriction Mapping
chemical_list: D004274:DNA, Recombinant; D046911:Macromolecular Substances