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Substrate Selectivity of Lysophospholipid Transporter LplT Involved in Membrane Phospholipid Remodeling in Escherichia coli.

Publication ,  Journal Article
Lin, Y; Bogdanov, M; Tong, S; Guan, Z; Zheng, L
Published in: J Biol Chem
January 29, 2016

Lysophospholipid transporter (LplT) was previously found to be primarily involved in 2-acyl lysophosphatidylethanolamine (lyso-PE) recycling in Gram-negative bacteria. This work identifies the potent role of LplT in maintaining membrane stability and integrity in the Escherichia coli envelope. Here we demonstrate the involvement of LplT in the recycling of three major bacterial phospholipids using a combination of an in vitro lysophospholipid binding assay using purified protein and transport assays with E. coli spheroplasts. Our results show that lyso-PE and lysophosphatidylglycerol, but not lysophosphatidylcholine, are taken up by LplT for reacylation by acyltransferase/acyl-acyl carrier protein synthetase on the inner leaflet of the membrane. We also found a novel cardiolipin hydrolysis reaction by phospholipase A2 to form diacylated cardiolipin progressing to the completely deacylated headgroup. These two distinct cardiolipin derivatives were both translocated with comparable efficiency to generate triacylated cardiolipin by acyltransferase/acyl-acyl carrier protein synthetase, demonstrating the first evidence of cardiolipin remodeling in bacteria. These findings support that a fatty acid chain is not required for LplT transport. We found that LplT cannot transport lysophosphatidic acid, and its substrate binding was not inhibited by either orthophosphate or glycerol 3-phosphate, indicating that either a glycerol or ethanolamine headgroup is the chemical determinant for substrate recognition. Diacyl forms of PE, phosphatidylglycerol, or the tetra-acylated form of cardiolipin could not serve as a competitive inhibitor in vitro. Based on an evolutionary structural model, we propose a "sideways sliding" mechanism to explain how a conserved membrane-embedded α-helical interface excludes diacylphospholipids from the LplT binding site to facilitate efficient flipping of lysophospholipid across the cell membrane.

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Published In

J Biol Chem

DOI

EISSN

1083-351X

Publication Date

January 29, 2016

Volume

291

Issue

5

Start / End Page

2136 / 2149

Location

United States

Related Subject Headings

  • Substrate Specificity
  • Protein Transport
  • Protein Structure, Secondary
  • Protein Binding
  • Phospholipid Transfer Proteins
  • Phospholipases A2
  • Phosphatidylglycerols
  • Mutation
  • Models, Molecular
  • Microscopy, Fluorescence
 

Citation

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Lin, Y., Bogdanov, M., Tong, S., Guan, Z., & Zheng, L. (2016). Substrate Selectivity of Lysophospholipid Transporter LplT Involved in Membrane Phospholipid Remodeling in Escherichia coli. J Biol Chem, 291(5), 2136–2149. https://doi.org/10.1074/jbc.M115.700419
Lin, Yibin, Mikhail Bogdanov, Shuilong Tong, Ziqiang Guan, and Lei Zheng. “Substrate Selectivity of Lysophospholipid Transporter LplT Involved in Membrane Phospholipid Remodeling in Escherichia coli.J Biol Chem 291, no. 5 (January 29, 2016): 2136–49. https://doi.org/10.1074/jbc.M115.700419.
Lin Y, Bogdanov M, Tong S, Guan Z, Zheng L. Substrate Selectivity of Lysophospholipid Transporter LplT Involved in Membrane Phospholipid Remodeling in Escherichia coli. J Biol Chem. 2016 Jan 29;291(5):2136–49.
Lin, Yibin, et al. “Substrate Selectivity of Lysophospholipid Transporter LplT Involved in Membrane Phospholipid Remodeling in Escherichia coli.J Biol Chem, vol. 291, no. 5, Jan. 2016, pp. 2136–49. Pubmed, doi:10.1074/jbc.M115.700419.
Lin Y, Bogdanov M, Tong S, Guan Z, Zheng L. Substrate Selectivity of Lysophospholipid Transporter LplT Involved in Membrane Phospholipid Remodeling in Escherichia coli. J Biol Chem. 2016 Jan 29;291(5):2136–2149.

Published In

J Biol Chem

DOI

EISSN

1083-351X

Publication Date

January 29, 2016

Volume

291

Issue

5

Start / End Page

2136 / 2149

Location

United States

Related Subject Headings

  • Substrate Specificity
  • Protein Transport
  • Protein Structure, Secondary
  • Protein Binding
  • Phospholipid Transfer Proteins
  • Phospholipases A2
  • Phosphatidylglycerols
  • Mutation
  • Models, Molecular
  • Microscopy, Fluorescence