Effect of phospholipid composition on activity of sodium-dependent leucine transport system in Pseudomonas aeruginosa.

The sodium-dependent leucine transport system of Pseudomonas aeruginosa was reconstituted into liposomes of specific polar head group composition. Na+-dependent counterflow and Na+ gradient-driven transport were measured as reconstituted transport activities. Proteoliposomes containing phosphatidylethanolamine exhibited increased transport activities. Phosphatidylglycerol, second to phosphatidylethanolamine, also enhanced the reconstituted transport activities. Proteoliposomes composed of phosphatidylcholine did not accumulate leucine. The enhanced transport activity by phosphatidylethanolamine was significantly influenced by its fatty acid composition. Dioleoylphosphatidylethanolamine was more effective in stimulating counterflow activity than dilauroylphosphatidylethanolamine. These results show that the leucine transport system of P. aeruginosa is sensitive to not only the polar head group composition but also the acyl group composition of phospholipids.