Phospholipase activity of Mycobacterium leprae harvested from experimentally infected armadillo tissue

Abstract

Three types of phospholipase activity--phospholipase A1, A2, and lysophospholipase--were detected in Mycobacterium leprae harvested from armadillo tissue at about 25% of the specific activity found in a slowly growing mycobacterium, Mycobacterium microti, which was grown in medium to optimize its phospholipase activity. The highest activity found was lysophospholipase, which released fatty acid from 2-lyso-phosphatidylcholine. Phospholipase activity was detected by using phosphatidylcholine and phosphatidylethanolamine. Differences in relative activities with these three types of substrate distinguished phospholipase activity in M. leprae extracts from armadillo liver extracts. Furthermore, retention of activity in M. leprae after NaOH treatment showed that the activity associated with M. leprae was not host derived. The specific activity of phospholipase was 20 times higher in extracts of M. leprae than in intact M. leprae organisms. Diazotization, a treatment which abolishes activities of surface enzymes exposed to the environment by the formation of covalent azide bonds with exposed amino groups, did not affect M. leprae's phospholipase activity, with one exception: release of arachidonic acid from phosphatidylcholine, which was partially inhibited. Phenolic glycolipid I, the major excreted amphipathic lipid of M. leprae, inhibited phospholipase activity, including release of arachidonic acid, for both M. leprae- and armadillo-derived activity.

Phospholipases C are involved in the virulence of Mycobacterium tuberculosis

“…, 1990). The relatively high phospholipase activities detected in mycobacteria harvested from host tissues (Wheeler and Ratledge, 1991; 1992) and the induction of the M. tuberculosis plc genes upon entry into phagocytic cells (Fig. 8) are consistent with these enzymes having a role in the release of fatty acids from host phospholipids.…”

“…, 1995), mycobacterial phospholipases C remain associated with the cell envelope (Fig. 6) (Wheeler and Ratledge, 1991) and are not released into the culture medium. This localization appears to contradict the role of these enzymes in the degradation of the phagosomal membrane.…”

Roles of Lipolytic enzymes in Mycobacterium tuberculosis pathogenesis

“…PLC might perform several functions related to virulence, such as releasing fatty acids from host phospholipids. The upregulation of Mtb plc genes upon entry into phagocytic cells ( Raynaud et al, 2002 ) and the comparatively high phospholipase activity in mycobacteria isolated from host tissues ( Wheeler and Ratledge, 1991 , 1992 ) align with this role. Several studies supporting this virulence-related function are as follows: Raynaud et al (2002) found that triple and quadruple plc-knock-out mutants of Mtb were attenuated during later infection stages in mice, underscoring the role of PLC in mycobacterial persistence within the host.…”