PMID:15661733
| Citation |
Harvat, EM, Zhang, YM, Tran, CV, Zhang, Z, Frank, MW, Rock, CO and Saier, MH Jr (2005) Lysophospholipid flipping across the Escherichia coli inner membrane catalyzed by a transporter (LplT) belonging to the major facilitator superfamily. J. Biol. Chem. 280:12028-34 |
|---|---|
| Abstract |
The transfer of phospholipids across membrane bilayers is protein-mediated, and most of the established transporters catalyze the energy-dependent efflux of phospholipids from cells. This work identifies and characterizes a lysophospholipid transporter gene (lplT, formally ygeD) in Escherichia coli that is an integral component in the 2-acylglycerophosphoethanolamine (2-acyl-GPE) metabolic cycle for membrane protein acylation. The lplT gene is adjacent to and in the same operon as the aas gene, which encodes the bifunctional enzyme 2-acyl-GPE acyltransferase/acyl-acyl carrier protein synthetase. In some bacteria, acyltransferase/acyl-ACP synthetase (Aas) and LplT homologues are fused in a single polypeptide chain. 2-Acyl-GPE transport to the inside of the cell was assessed by measuring the Aas-dependent formation of phosphatidylethanolamine. The Aas-dependent incorporation of [3H]palmitate into phosphatidylethanolamine was significantly diminished in deltalplT mutants, and the LplT-Aas transport/acylation activity was independent of the proton motive force. The deltalplT mutants accumulated acyl-GPE in vivo and had a diminished capacity to transport exogenous 2-acylglycerophosphocholine into the cell. Spheroplasts prepared from wild-type E. coli transported and acylated fluorescent 2-acyl-GPE with an apparent K(d) of 7.5 microM, whereas this high-affinity process was absent in deltalplT mutants. Thus, LplT catalyzes the transbilayer movement of lysophospholipids and is the first example of a phospholipid flippase that belongs to the major facilitator superfamily. |
| Links |
PubMed Online version:10.1074/jbc.M414368200 |
| Keywords |
Carbon-Sulfur Ligases/physiology; Catalysis; Cell Membrane/metabolism; Escherichia coli/metabolism; Escherichia coli Proteins/physiology; Fatty Acids/metabolism; Lipid Bilayers/metabolism; Lysophospholipids/metabolism; Phospholipid Transfer Proteins/physiology |
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