M. tuberculosis Rv2252 encodes a diacylglycerol kinase involved in the biosynthesis of phosphatidylinositol mannosides (PIMs)

Phosphorylated lipids play important roles in biological systems, not only as structural moieties but also as modulators of cellular function. Phospholipids of pathogenic bacteria are known to play roles both as membrane components and as factors that modulate the infectious process. Mycobacterium tuberculosis is, however, noteworthy in that it has an extremely diverse repertoire of biologically active phosphorylated lipids that, in the absence of a specialized protein translocation system, appear to constitute the main means of communication with the host. Many of these lipids are derived from phosphatidylinositol (PI) that is differentially processed to give rise to phosphatidylinositol mannosides (PIMs) or lipoarabinomannan. In preliminary studies on the lipid processing enzymes associated with the bacterial cell wall, a kinase activity was noted that gave rise to a novel lipid species released by the bacterium. It was determined that this kinase activity was encoded by the ORF Rv2252. Rv2252 demonstrates the capacity to phosphorylate various amphipathic lipids of host and bacterial origin, in particular a M. tuberculosis derived diacylglycerol. Targeted deletion of the rv2252 gene resulted in disruption of the production of certain higher order PIM species, suggesting a role for Rv2252 in the biosynthetic pathway of PI, a PIM precursor.