title: Phospholipases C are involved in the virulence of Mycobacterium tuberculosis.
abstract: Phospholipases C play a role in the pathogenesis of several bacteria. Mycobacterium tuberculosis, the causative agent of tuberculosis, possesses four genes encoding putative phospholipases C, plcA, plcB, plcC and plcD. However, the contribution of these genes to virulence is unknown. We constructed four single mutants of M. tuberculosis each inactivated in one of the plc genes, a triple plcABC mutant and a quadruple plcABCD mutant. The mutants all exhibited a lower phospholipase C activity than the wild-type parent strain, demonstrating that the four plc genes encode a functional phospholipase C in M. tuberculosis. Functional complementation of the Delta plcABC triple mutant with the individual plcA, plcB and plcC genes restored in each case about 20% of the total Plc activity detected in the parental strain, suggesting that the three enzymes contribute equally to the overall Plc activity of M. tuberculosis. RT-PCR analysis of the plc genes transcripts showed that the expression of these genes is strongly upregulated during the first 24 h of macrophage infection. Moreover, the growth kinetics of the triple and quadruple mutants in a mouse model of infection revealed that both mutants are attenuated in the late phase of the infection emphasizing the importance of phospholipases C in the virulence of the tubercle bacillus.
authors.affiliation: Unité de Génétique Mycobactérienne, Institut Pasteur, Paris, France. cathraynaud@yahoo.fr
authors.forename: Catherine
authors.initials: C
authors.lastname: Raynaud
authors.forename: Christophe
authors.initials: C
authors.lastname: Guilhot
authors.forename: Jean
authors.initials: J
authors.lastname: Rauzier
authors.forename: Yann
authors.initials: Y
authors.lastname: Bordat
authors.forename: Vladimir
authors.initials: V
authors.lastname: Pelicic
authors.forename: Riccardo
authors.initials: R
authors.lastname: Manganelli
authors.forename: Issar
authors.initials: I
authors.lastname: Smith
authors.forename: Brigitte
authors.initials: B
authors.lastname: Gicquel
authors.forename: Mary
authors.initials: M
authors.lastname: Jackson
mesh_terms: D000818:Animals; D002460:Cell Line; D005260:Female; D005798:Genes, Bacterial; D006801:Humans; D008264:Macrophages / Q000382:microbiology; D051379:Mice; D008807:Mice, Inbred BALB C; D005810:Multigene Family; D009154:Mutation; D009169:Mycobacterium tuberculosis / Q000201:enzymology / Q000235:genetics / Q000472:pathogenicity*; D014397:Tuberculosis, Pulmonary / Q000382:microbiology / Q000503:physiopathology*; D010738:Type C Phospholipases / Q000096:biosynthesis* / Q000235:genetics; D014774:Virulence
chemical_list: D010738:Type C Phospholipases