title: Legionella pneumophila exhibits plasminogen activator activity.
abstract: Based on their localization at the boundary of the bacterial cell and its environment, outer-membrane proteins (Omps) are important determinants for interaction of bacteria with their host cell. Therefore, they can be considered as important determinants for virulence. Looking for Legionella pneumophila Omps potentially involved in virulence, we identified a gene encoding a homologue of the plasminogen activator (Pla) of Yersinia pestis. Pla belongs to the class of omptins, a family of surface proteases/adhesins that exhibit different virulence-associated functions. In this report we describe the cloning and identification of the plasminogen activator homologue Lpa of L. pneumophila and demonstrate its outer-membrane localization. Transcriptional analysis of the Lpa region revealed expression of the gene in both exponential and stationary growth phase and showed that transcription of the lpa gene is directed by its own promoter. We also show, to our knowledge for the first time, that L. pneumophila has the capacity to convert plasminogen into plasmin by the action of the outer-membrane Lpa protein.
authors.affiliation: Laboratory for Bacteriology, Rega Institute for Medical Research, Katholieke Universiteit Leuven, Minderbroedersstraat 10, B-3000 Leuven, Belgium.
authors.forename: Leen
authors.initials: L
authors.lastname: Vranckx
authors.affiliation: Laboratory for Bacteriology, Rega Institute for Medical Research, Katholieke Universiteit Leuven, Minderbroedersstraat 10, B-3000 Leuven, Belgium.
authors.forename: Emmy
authors.initials: E
authors.lastname: De Buck
authors.affiliation: Laboratory for Bacteriology, Rega Institute for Medical Research, Katholieke Universiteit Leuven, Minderbroedersstraat 10, B-3000 Leuven, Belgium.
authors.forename: Jozef
authors.initials: J
authors.lastname: Anné
authors.affiliation: Laboratory for Bacteriology, Rega Institute for Medical Research, Katholieke Universiteit Leuven, Minderbroedersstraat 10, B-3000 Leuven, Belgium.
authors.forename: Elke
authors.initials: E
authors.lastname: Lammertyn
mesh_terms: D000595:Amino Acid Sequence; D000656:Amoeba / Q000382:microbiology; D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D015964:Gene Expression Regulation, Bacterial; D016952:Legionella pneumophila / Q000235:genetics / Q000254:growth & development / Q000378:metabolism* / Q000502:physiology; D010447:Peptide Hydrolases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D010958:Plasminogen / Q000378:metabolism*; D010960:Plasminogen Activators / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017422:Sequence Analysis, DNA
chemical_list: D001425:Bacterial Outer Membrane Proteins; D010958:Plasminogen; D010447:Peptide Hydrolases; D010960:Plasminogen Activators