title: Expression of the Pasteurella haemolytica leukotoxin is inhibited by a locus that encodes an ATP-binding cassette homolog.
abstract: Multicopy and single-copy chromosomal fusions between the Pasteurella haemolytica leukotoxin regulatory region and the Escherichia coli beta-galactosidase gene have been constructed. These fusions were used as reporters to identify and isolate regulators of leukotoxin expression from a P. haemolytica cosmid library. A cosmid clone, which inhibited leukotoxin expression from multicopy and single-copy protein fusions, was isolated and found to contain the complete leukotoxin gene cluster plus additional upstream sequences. The locus responsible for inhibition of expression from leukotoxin-beta-galactosidase fusions was mapped within these upstream sequences, by transposon mutagenesis with Tn5, and its DNA sequence was determined. The inhibitory activity was found to be associated with a predicted 440-amino-acid reading frame (lapA) that lies within a four-gene arginine transport locus. LapA is predicted to be the nucleotide-binding component of this transport system and shares homology with the Clp family of proteases.
authors.affiliation: Department of Microbiology and Immunology, Baylor College of Medicine, Houston, Texas 77030.
authors.forename: S K
authors.initials: SK
authors.lastname: Highlander
authors.forename: E A
authors.initials: EA
authors.lastname: Wickersham
authors.forename: O
authors.initials: O
authors.lastname: Garza
authors.forename: G M
authors.initials: GM
authors.lastname: Weinstock
mesh_terms: D049069:ATP-Dependent Proteases; D000251:Adenosine Triphosphatases / Q000235:genetics*; D000595:Amino Acid Sequence; D001427:Bacterial Toxins / Q000235:genetics*; D001483:Base Sequence; D002874:Chromosome Mapping; D004269:DNA, Bacterial / Q000737:chemistry; D005098:Exotoxins / Q000235:genetics*; D005798:Genes, Bacterial; D006360:Heat-Shock Proteins / Q000235:genetics*; D007763:Lac Operon; D016978:Mannheimia haemolytica / Q000235:genetics / Q000472:pathogenicity*; D008969:Molecular Sequence Data; D005810:Multigene Family; D011993:Recombinant Fusion Proteins / Q000235:genetics; D012697:Serine Endopeptidases / Q000235:genetics*
chemical_list: D001427:Bacterial Toxins; D004269:DNA, Bacterial; D005098:Exotoxins; D006360:Heat-Shock Proteins; D011993:Recombinant Fusion Proteins; C018579:leukotoxin; D049069:ATP-Dependent Proteases; D012697:Serine Endopeptidases; D000251:Adenosine Triphosphatases