Multiple lysophosphatidic acid acyltransferases in Neisseria meningitidis

Lysophosphatidic acid (LPA) and phosphatidic acid (PA) are critical phospho lipid intermediates In the biosynthesis of cell membranes. In Escherichia c oil, LPA acyltransferase (1-acyl-sn-glycerol-3-phosphate acyltransferase; E C 2.3.1.51) catalyses the transfer of an acyl chain from either acyl-coenzy me A or acyl-acyl carrier protein onto LPA to produce PA. While E. coil pos sesses one essential LPA acyltransferase (PlsC), Neisseria meningitidis pos sesses at least two LPA acyltransferases. This study describes the identifi cation and characterization of nlaB (neisserial LPA acyltransferase B) , th e second LPA acyltransferase identified in N. meningitidis. The gene was lo cated downstream of the Tn916 insertion in N. meningitidis mutant 469 and d iffered in nucleotide and predicted amino acid sequence from the previously characterized neisserial LPA acyltransferase homologue nlaA. nlaB has spec ific IPA acyltransferase activity, as demonstrated by complementation of an E. coil plsC(Ts) mutant in trans, by decreased levels of LPA acyitransfera se activity in nlaB mutants and by lack of complementation of E, coil plsB2 6,X50, a mutant defective in the first acyltransferase step in phospholipid biosynthesis. Meningococcal nlaA mutants accumulated LPA and demonstrated alterations in membrane phospholipid composition, yet retained LPA acyltran sferase activity. In contrast, meningococcal nlaB mutants exhibited decreas ed LPA acyltransferase activity, but did not accumulate LPA or display any of her observable membrane changes. We propose that N. meningitidis possess es at: least two LPA acyltransferases to provide for the production of a gr eater diversity of membrane phospholipids.