Summary auto-generated
This study analyzed the membrane lipids of four Listeria species (L. innocua, L. monocytogenes, L. seeligeri, and L. welshimeri) using chromatography and mass spectrometry. The researchers identified a novel lipid structure called L-lysylcardiolipin (L-lysyl-substituted bis(phosphatidyl)glycerol) that had not been previously found in nature. All four species contained similar polar lipid compositions dominated by phospholipids, including phosphatidylglycerol, L-lysylphosphatidylglycerol, cardiolipin, and L-lysylcardiolipin. During late exponential growth, cardiolipin and L-lysylcardiolipin increased to 47-78% of total lipid phosphorus. The study also identified several other phospholipids including glycerophosphoglycolipids and a tentative polyprenol phosphate. Fast atom bombardment-mass spectrometry revealed that both cardiolipin and L-lysylcardiolipin consisted of five molecular species with different fatty acid combinations. The authors propose that L-lysylcardiolipin may serve as a genus-specific chemotaxonomic marker for Listeria.
Key findings
- L-lysylcardiolipin, a novel lipid structure never previously found in nature, is present in all four Listeria species tested and represents a characteristic component of the L. monocytogenes lineage
- Four lysine-containing phospholipids were identified in Listeria species, along with phosphatidylglycerol, cardiolipin, glycerophosphoglycolipids, and other unique phospholipids
- Cardiolipin and L-lysylcardiolipin increase dramatically toward stationary phase, reaching 47-78% of total lipid phosphorus, with L-lysylcardiolipin-to-cardiolipin ratios varying between 0.25-1.6
- Both cardiolipin and L-lysylcardiolipin exist as five distinct molecular species due to different combinations of branched fatty acids (predominantly anteiso- and iso-branched types)
- L-lysylcardiolipin may serve as a potential genus-specific chemotaxonomic marker for distinguishing Listeria species, pending further studies on other descent lines
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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.