Evolution of the chaperone/usher assembly pathway: fimbrial classification goes Greek.
Many Proteobacteria use the chaperone/usher pathway to assemble proteinaceous filaments on the bacterial surface. These filaments can curl into fimbrial or nonfimbrial surface structures (e.g., a capsule or spore coat). This article reviews the phylogeny of operons belonging to the chaperone/usher assembly class to explore the utility of establishing a scheme for subdividing them into clades of phylogenetically related gene clusters. Based on usher amino acid sequence comparisons, our analysis shows that the chaperone/usher assembly class is subdivided into six major phylogenetic clades, which we have termed alpha-, beta-, gamma-, kappa-, pi-, and sigma-fimbriae. Members of each clade share related operon structures and encode fimbrial subunits with similar protein domains. The proposed classification system offers a simple and convenient method for assigning newly discovered chaperone/usher systems to one of the six major phylogenetic groups.
Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, One Shields Ave., Davis, CA 95616-8645, USA.
Sean-Paul
SP
Nuccio
Andreas J
AJ
Bäumler
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D019143:Evolution, Molecular; D010861:Fimbriae, Bacterial / Q000145:classification* / Q000235:genetics / Q000378:metabolism; D005798:Genes, Bacterial; D018832:Molecular Chaperones / Q000235:genetics* / Q000378:metabolism; D005810:Multigene Family; D009876:Operon; D010802:Phylogeny; D020560:Proteobacteria / Q000235:genetics* / Q000378:metabolism*
D001426:Bacterial Proteins; D018832:Molecular Chaperones