Polar lipids of four Listeria species containing L-lysylcardiolipin, a novel lipid structure, and other unique phospholipids

Abstract

The membrane lipids of Listeria innocua, Listeria monocytogenes, Listeria seeligeri and Listeria welshimeri were fractionated on DEAE-cellulose and purified by chromatography on silica gel and/or preparative TLC. The lipid structures were elucidated by chemical and chromatographic means. The polar lipid composition of the four listeria species was similar. Phospholipids predominated. They consisted of phosphatidylglycerol, L-lysylphosphatidylglycerol, cardiolipin [bis(phosphatidyl)glycerol] and L-lysylcardiolipin. A phospholipid more polar than cardiolipin, possibly two L-lysyl derivatives of it, sn-glycero-1-phosphoglycolipid, its D-alanyl derivative, and polyprenol phosphate were also detected. Towards the end of exponential growth, the relative amounts of cardiolipin and L-lysylcardiolipin increased, approaching 47-78% lipid phosphorus with a ratio of L-lysylcardiolipin to cardiolipin of 0.25-1.6. As shown by fast atom bombardment-mass spectrometry, cardiolipin and L-lysylcardiolipin consisted of five molecular species due to various fatty acid combinations. L-lysylcardiolipin has so far not been found in nature. It belongs to the recently discovered class of substituted cardiolipins. Its occurrence in the four listeria species tested shows that it is a characteristic lipid component of the L. monocytogenes line of descent. Further studies on the lipid pattern of members of the other descent line are required to decide whether lysylcardiolipin can serve as a genus-specific chemotaxonomic marker for listeriae.