We investigated the insertion- and deletion-associated genetic diversity in all four plc genes among 682 epidemiologically and clinically well-characterized M. tuberculosis clinical isolates using PCR, DNA sequencing, and Southern hybridization.
The precise role of phospholipase C in the pathogenicity of M. tuberculosis is unknown, but considering the potential importance that the plc genes may have in the virulence of the tubercle bacillus, the study of isolates cultured from patients with active tuberculosis bearing genetic variations affecting these genes may provide insights into the significance of phospholipase C enzymes for tuberculosis pathogenicity.
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.
Previous studies have reported multiple copies of plc genes homologous to Pseudomonas aeruginosa plcH and plcN genes encoding the hemolytic and nonhemolytic phospholipase C enzymes in the genomes of Mycobacterium tuberculosis, M. marinum, M. bovis, and M. ulcerans.