title: Deletion analysis resolves cell-binding and lytic domains of the Pasteurella leukotoxin.
abstract: A series of internal deletions in the lktA gene of Pasteurella haemolytica has been constructed. All of the deletions eliminated the lytic activity of the leukotoxin towards the bovine lymphoma cell line, BL-3. Deletions removing segments of the amino-proximal hydrophobic region, which is thought to constitute an essential membrane-spanning domain, were found to agglutinate BL-3 cells. Agglutination was similar to lysis by the wild-type toxin in that it was dependent upon the presence of calcium and required expression of the lktC gene. The agglutinating deletion proteins protected BL-3 cells from lysis by the wild-type toxin in a competitive fashion. This suggests that these mutants bind to a surface feature of the leukocyte which interacts with the native leukotoxin. These findings demonstrate that the cell-binding and lytic domains of the leukotoxin are separable.
authors.affiliation: Department of Medical Biochemistry and Genetics, College of Medicine, Texas A & M University, College Station 77843.
authors.forename: W T
authors.initials: WT
authors.lastname: Cruz
authors.forename: R
authors.initials: R
authors.lastname: Young
authors.forename: Y F
authors.initials: YF
authors.lastname: Chang
authors.forename: D K
authors.initials: DK
authors.lastname: Struck
mesh_terms: D000818:Animals; D001427:Bacterial Toxins / Q000235:genetics*; D002417:Cattle; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D002872:Chromosome Deletion; D003062:Codon / Q000235:genetics; D005098:Exotoxins / Q000235:genetics* / Q000378:metabolism / Q000494:pharmacology; D005798:Genes, Bacterial; D008223:Lymphoma; D016297:Mutagenesis, Site-Directed; D010325:Pasteurella / Q000235:genetics* / Q000378:metabolism; D010957:Plasmids
chemical_list: D001427:Bacterial Toxins; D003062:Codon; D005098:Exotoxins; C018579:leukotoxin