title: The Caulobacter crescentus holdfast: identification of holdfast attachment complex genes.
abstract: Caulobacters are biofilm bacteria that attach to surfaces via a holdfast, an adhesive expressed at discrete cell surface sites. We have described a cluster of at least three genes involved in the adhesive attachment of the holdfast of Caulobacter crescentus CB2A to the cell, analyzing the sequence of two genes, hfaAB. Here we report hfaC and a fourth open reading frame, hfaD. hfaC predicts a protein of 41 kDa homologous to ATP-binding transport-related proteins, with ChvD of Agrobacterium tumefaciens as best match. HfaD is predicted to be 28 kDa with three membrane spanning regions. hfaA, hfaC, and hfaD were expressed in Escherichia coli; Western analysis with antisera against a holdfast-enriched preparation indicated HfaA was likely holdfast-associated. Cumulative findings predict HfaA and HfaB are developmentally regulated and one or both enhance hfaC transcription, HfaA is a mediator of adhesion, possibly between holdfast and a membrane-bound HfaD, and HfaC mediates export of an unidentified component required for holdfast attachment.
authors.affiliation: Department of Microbiology, University of British Columbia, Vancouver, Canada.
authors.forename: H D
authors.initials: HD
authors.lastname: Kurtz
authors.forename: J
authors.initials: J
authors.lastname: Smit
authors.forename: J
authors.initials: J
authors.lastname: Smith
mesh_terms: D000595:Amino Acid Sequence; D001422:Bacterial Adhesion / Q000235:genetics*; D001426:Bacterial Proteins / Q000032:analysis / Q000737:chemistry / Q000235:genetics*; D001483:Base Sequence; D015153:Blotting, Western; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics*; D016935:Caulobacter crescentus / Q000235:genetics*; D005798:Genes, Bacterial / Q000235:genetics*; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics*; D008969:Molecular Sequence Data; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; C086642:HfaC protein, Caulobacter crescentus; C086643:HfaD protein, Caulobacter crescentus; D008565:Membrane Proteins