title: impA, a gene coding for an inner membrane protein, influences colonial morphology of Actinobacillus actinomycetemcomitans.
abstract: Directed mutagenesis of a gene coding for a membrane protein of the periodontopathogen Actinobacillus actinomycetemcomitans was achieved by conjugation. The gene was disrupted by insertion of an antibiotic cassette into a unique endonuclease restriction sequence engineered by inverse PCR. The disrupted gene was cloned into a conjugative plasmid and transferred from Escherichia coli to A. actinomycetemcomitans. The allelic replacement mutation resulted in the loss of a 22-kDa inner membrane protein. The loss of this protein (ImpA) resulted in changes in the outer membrane protein composition of the bacterium. Concurrent with the mutation in impA was a change in the pattern of growth of the mutant bacteria in broth cultures. The progenitor bacteria grew as a homogeneous suspension of cells compared to a granular, autoaggregating adherent cell population described for the mutant bacteria. These data suggest that ImpA may play a regulatory role or be directly involved in protein(s) that are exported and associated with colony variations in A. actinomycetemcomitans.
authors.affiliation: Department of Microbiology and Molecular Genetics, The Markey Center for Molecular Genetics, College of Medicine and College of Agriculture and Life Sciences, University of Vermont, Burlington, Vermont 05405, USA. kmintz@zoo.uvm.edu
authors.forename: K P
authors.initials: KP
authors.lastname: Mintz
authors.forename: P M
authors.initials: PM
authors.lastname: Fives-Taylor
mesh_terms: D016976:Aggregatibacter actinomycetemcomitans / Q000235:genetics* / Q000254:growth & development; D000483:Alleles; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D015152:Blotting, Northern; D003227:Conjugation, Genetic; D008969:Molecular Sequence Data; D016296:Mutagenesis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012697:Serine Endopeptidases
chemical_list: D001426:Bacterial Proteins; D012697:Serine Endopeptidases; C065791:impA protein, Salmonella typhimurium