Molecular packing of cord factor and its interaction with phosphatidylinositol in mixed monolayers.
Cord factor (trehalose 6,6'-dimycolate, CF) is a glycolipid located in the outer mycobacterial cell wall that is implicated in the pathogenesis of mycobacteria. Furthermore, CF is a convenient model for studying mycolic acid residues, the major lipid constituents of the mycobacterial cell wall that are believed to form a barrier against drug penetration. The surface properties of CF and its interactions with phosphatidylinositol (PI) have been investigated using the monolayer technique. During compression/expansion/recompression cycles, CF monolayers switch from a loosely packed to a more tightly packed structure. The change in surface properties suggests a molecular rearrangement, perhaps involving interdigitation of long and short chains of the CF molecules. In CF-PI monolayers, maximal lateral packing density occurs between 0.5 and 0.7 mole fraction CF, which is close to the relative composition of mycolic acid residues and shorter-chain lipids in the mycobacterial cell wall. Low concentrations of CF increase the order in PI monolayers, consistent with CF toxicity involving rigidification of cell membranes.
Almog
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Division of Molecular Medicine, Wadsworth Center, New York State Department of Health, Albany, USA.
Mannella
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CA
D003311:Cord Factors / Q000737:chemistry*; D007700:Kinetics; D008051:Lipid Bilayers / Q000737:chemistry*; D008961:Models, Structural; D015394:Molecular Structure; D009169:Mycobacterium tuberculosis; D010716:Phosphatidylinositols / Q000737:chemistry*; D012044:Regression Analysis; D013329:Structure-Activity Relationship; D013499:Surface Properties
D003311:Cord Factors; D008051:Lipid Bilayers; D010716:Phosphatidylinositols