title: Studies on the production of quorum-sensing signal molecules in Mannheimia haemolytica A1 and other Pasteurellaceae species.
abstract: The bioluminescence assay system using Vibrio harveyi reporter strains were used to examine quorum-sensing autoinducer (AI) activity from Mannheimia haemolytica A1 cell-free culture supernatant. We showed that M. haemolytica A1 cell-free culture supernatant contains molecules that can stimulate the quorum-sensing system that regulates the expression of the luciferase operon in V. harveyi. Specifically, M. haemolytica A1 can stimulate only the quorum system 2 but not system 1, suggesting that the culture supernatant only contains molecules similar to AI-2 of V. harveyi. The bioluminescence assay was also used to show that culture supernatants from related Pasteurellaceae organisms, Pasteurella multocida, Pasteurella trehalosi, Actinobacillus suis and Actinobacillus pleuropneumoniae, also contain AI-2-like molecules. This is consistent with the presence of a luxS homolog in the genomes of P. multocida and A. pleuropneumoniae. A luxS homolog was cloned by PCR from M. haemolytica A1 using sequencing data from the ongoing genome sequencing project. The cloned luxS(M.h.) was able to complement AI-2 production in the Escherichia coli DH5alpha luxS mutant. This is the first report of a quorum-sensing activity in M. haemolytica A1 and suggests that this bacterium utilizes this mechanism to regulate expression of genes under specific conditions.
authors.affiliation: Department of Microbiology, University of Guelph, N1G 2W1, Guelph, ON, Canada.
authors.forename: Rebecca J
authors.initials: RJ
authors.lastname: Malott
authors.forename: Reggie Y C
authors.initials: RY
authors.lastname: Lo
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D013437:Carbon-Sulfur Lyases; D002417:Cattle; D015964:Gene Expression Regulation, Bacterial; D006714:Homoserine / Q000031:analogs & derivatives* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007783:Lactones / Q000378:metabolism*; D008163:Luminescent Measurements; D015661:Pasteurellaceae / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D015398:Signal Transduction; D014733:Vibrio / Q000235:genetics / Q000254:growth & development / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D007783:Lactones; C091088:N-octanoylhomoserine lactone; D006714:Homoserine; D013437:Carbon-Sulfur Lyases; C117753:LuxS protein, Bacteria