| Proper fatty acid composition rather than an ionizable lipid amine is required for full transport function of lactose permease from Escherichia coli. | |
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MedLine Citation:
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PMID: 23322771 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Energy-dependent uphill transport but not energy-independent downhill transport by lactose permease (LacY) is impaired when expressed in Escherichia coli cells or reconstituted in liposomes lacking phosphatidylethanolamine (PE) and containing only anionic phospholipids. The absence of PE results in inversion of the N-terminal half and misfolding of periplasmic domain P7, which are required for uphill transport of substrates. Replacement of PE in vitro by lipids with no net charge (phosphatidylcholine (PC), monoglucosyl diacylglycerol (GlcDAG), or diglucosyl diacylglycerol (GlcGlcDAG)) supported wild type transmembrane topology of the N-terminal half of LacY. The restoration of uphill transport in vitro was dependent on LacY native topology and proper folding of P7. Support of uphill transport by net neutral lipids in vitro (PE > PC ≫ GlcDAG ≠ GlcGlcDAG provided that PE or PC contained one saturated fatty acid) paralleled the results observed previously in vivo (PE = PC > GlcDAG ≠ GlcGlcDAG). Therefore, a free amino group is not required for uphill transport as previously concluded based on the lack of in vitro uphill transport when fully unsaturated PC replaced E. coli-derived PE. A close correlation was observed in vivo and in vitro between the ability of LacY to carry out uphill transport, the native conformation of P7, and the lipid headgroup and fatty acid composition. Therefore, the headgroup and the fatty acid composition of lipids are important for defining LacY topological organization and catalytically important structural features, further illustrating the direct role of lipids, independent of other cellular factors, in defining membrane protein structure/function. |
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Authors:
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Heidi Vitrac; Mikhail Bogdanov; William Dowhan |
Publication Detail:
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Type: Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't Date: 2013-01-15 |
Journal Detail:
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Title: The Journal of biological chemistry Volume: 288 ISSN: 1083-351X ISO Abbreviation: J. Biol. Chem. Publication Date: 2013 Feb |
Date Detail:
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Created Date: 2013-02-25 Completed Date: 2013-04-25 Revised Date: 2013-04-26 |
Medline Journal Info:
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Nlm Unique ID: 2985121R Medline TA: J Biol Chem Country: United States |
Other Details:
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Languages: eng Pagination: 5873-85 Citation Subset: IM |
Affiliation:
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Department of Biochemistry and Molecular Biology, University of Texas Medical School, Houston, Texas 77030, USA. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Amines
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chemistry* Biological Transport Catalysis Cell Membrane / metabolism Densitometry / methods Epitopes / chemistry Escherichia coli / enzymology*, metabolism Escherichia coli Proteins / chemistry*, metabolism Fatty Acids / chemistry* Gene Expression Regulation, Bacterial Gene Expression Regulation, Enzymologic Lipids / chemistry* Membrane Transport Proteins / chemistry* Monosaccharide Transport Proteins / chemistry*, metabolism Phosphatidylethanolamines / chemistry Protein Binding Proteolipids / metabolism Symporters / chemistry*, metabolism |
| Grant Support | |
ID/Acronym/Agency:
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GM R37 20478/GM/NIGMS NIH HHS; R37 GM020478/GM/NIGMS NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Amines; 0/Epitopes; 0/Escherichia coli Proteins; 0/Fatty Acids; 0/LacY protein, E coli; 0/Lipids; 0/Membrane Transport Proteins; 0/Monosaccharide Transport Proteins; 0/Phosphatidylethanolamines; 0/Proteolipids; 0/Symporters; 0/proteoliposomes; 39382-08-6/phosphatidylethanolamine; 9068-45-5/lactose permease |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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