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DOI	10.1073/pnas.1714668115
	Lipid bilayer composition modulates the unfolding free energy of a knotted α-helical membrane protein
	Sanders M.R.; Findlay H.E.; Booth P.J.
发表日期	2018
ISSN	0027-8424
起始页码	E1709
结束页码	E1808
卷号	115 期号:8
英文摘要	α-Helical membrane proteins have eluded investigation of their thermodynamic stability in lipid bilayers. Reversible denaturation curves have enabled some headway in determining unfolding free energies. However, these parameters have been limited to detergent micelles or lipid bicelles, which do not possess the same mechanical properties as lipid bilayers that comprise the basis of natural membranes. We establish reversible unfolding of the membrane transporter LeuT in lipid bilayers, enabling the comparison of apparent unfolding free energies in different lipid compositions. LeuT is a bacterial ortholog of neurotransmitter transporters and contains a knot within its 12-transmembrane helical structure. Urea is used as a denaturant for LeuT in proteoliposomes, resulting in the loss of up to 30% helical structure depending upon the lipid bilayer composition. Urea unfolding of LeuT in liposomes is reversible, with refolding in the bilayer recovering the original helical structure and transport activity. A linear dependence of the unfolding free energy on urea concentration enables the free energy to be extrapolated to zero denaturant. Increasing lipid headgroup charge or chain lateral pressure increases the thermodynamic stability of LeuT. The mechanical and charge properties of the bilayer also affect the ability of urea to denature the protein. Thus, we not only gain insight to the long–sought-after thermodynamic stability of an α-helical protein in a lipid bilayer but also provide a basis for studies of the folding of knotted proteins in a membrane environment. © 2018 National Academy of Sciences. All Rights Reserved.
英文关键词	Membrane proteins; Protein folding; Protein–lipid interactions
语种	英语
scopus关键词	alpha helical membrane protein; liposome; membrane protein; membrane transporter LeuT; unclassified drug; urea; bacterial protein; membrane protein; alpha helix; Article; concentration (parameters); controlled study; energy; lipid bilayer; lipid composition; nonhuman; priority journal; protein denaturation; protein function; protein refolding; protein secondary structure; protein stability; protein transport; protein unfolding; regulatory mechanism; thermodynamic stability; thermodynamics; chemistry; lipid bilayer; molecular model; protein conformation; protein unfolding; Bacterial Proteins; Lipid Bilayers; Membrane Proteins; Models, Molecular; Protein Conformation; Protein Denaturation; Protein Unfolding; Thermodynamics
来源期刊	Proceedings of the National Academy of Sciences of the United States of America
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/160541
作者单位	Sanders, M.R., Department of Chemistry, King’s College London, London, SE1 1DB, United Kingdom; Findlay, H.E., Department of Chemistry, King’s College London, London, SE1 1DB, United Kingdom; Booth, P.J., Department of Chemistry, King’s College London, London, SE1 1DB, United Kingdom
推荐引用方式 GB/T 7714	Sanders M.R.,Findlay H.E.,Booth P.J.. Lipid bilayer composition modulates the unfolding free energy of a knotted α-helical membrane protein[J],2018,115(8).
APA	Sanders M.R.,Findlay H.E.,&Booth P.J..(2018).Lipid bilayer composition modulates the unfolding free energy of a knotted α-helical membrane protein.Proceedings of the National Academy of Sciences of the United States of America,115(8).
MLA	Sanders M.R.,et al."Lipid bilayer composition modulates the unfolding free energy of a knotted α-helical membrane protein".Proceedings of the National Academy of Sciences of the United States of America 115.8(2018).