DOI: 10.1073/pnas.1714668115
论文题名: Lipid bilayer composition modulates the unfolding free energy of a knotted α-helical membrane protein
作者: Sanders M.R. ; Findlay H.E. ; Booth P.J.
刊名: Proceedings of the National Academy of Sciences of the United States of America
ISSN: 0027-8424
出版年: 2018
卷: 115, 期: 8 起始页码: E1709
结束页码: E1808
语种: 英语
英文关键词: Membrane proteins
; Protein folding
; Protein–lipid interactions
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
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. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/163739
Appears in Collections: 气候变化与战略
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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
Recommended Citation:
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]. Proceedings of the National Academy of Sciences of the United States of America,2018-01-01,115(8)