Phospholipases C are involved in the virulence of Mycobacterium tuberculosis

Abstract

Summary 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 ΔplcABC 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.

Characterization of two distinct phospholipase C enzymes from Burkholderia pseudomallei

“…As noted earlier, other organisms, such as L. monocytogenes (Mengaud et al, 1991;Raveneau et al, 1992) and Mycobacterium tuberculosis (Raynaud et al, 2002), carry up to four genes encoding PLCs. It is likely that these PLC enzymes have different roles or act at different stages of host infection as do PLCs reported for other bacteria (Mengaud et al, 1991;Raveneau et al, 1992;Raynaud et al, 2002). Perhaps the Mutant constructions and effect of plc mutation on multiplication in culture medium B. pseudomallei plc mutants were constructed and verified (Fig.…”

β-Lactamase can function as a reporter of bacterial protein export during Mycobacterium tuberculosis infection of host cells

“…Mpt83 has a predicted Sec signal sequence with a lipoprotein signal peptidase (LspA) cleavage site and the requisite conserved cysteine for lipid modification. PlcB (Rv2350c, phospholipase C) is a cell-wall-associated protein of M. tuberculosis shown to function in virulence (Johansen et al, 1996;Raynaud et al, 2002). Unlike Mpt63 and Mpt83, PlcB has a predicted Tat signal sequence including a twin-arginine motif (Dilks et al, 2003).…”

“…Finally, we tested the signal sequence of PlcB, a proven cellwall-associated phospholipase C, for the ability to promote export of enzymically active 9BlaTEM-1 (Johansen et al, 1996;Raynaud et al, 2002). PlcB has a predicted Tat signal sequence, and the ssPlcB-9BlaTEM-1 fusion also allowed DblaC M. tuberculosis to grow in the presence of carbenicillin (Fig.…”

Virulence Factors and Pathogenicity of Mycobacterium

“…M. smegmatis deletion mutants to tatC and tatA showed a growth defect on agar, defective exportation to active beta-lactamases and hypersensitivity to sodium dodecyl sulfate (SDS), reason that suggests that TAT genes could be good candidates for vaccines and drug development [40]. Mycobacterial phospholipases, virulence-related molecules encoding by plcA, plcB, plcC and plcD genes, are secreted by the twin-arginine transporter [41]. TAT system is involved in secretion of relevant proteins, as example; the secreted protein encoded by the Rv2525c gene, which is involved in the cell wall biogenesis, this protein is conserved in M. leprae and present in MTB, it has been described as important for virulence and it is involved in the resistance to beta-lactam antibiotics [42].…”