title: Structural investigation of the transmembrane domain of KCNE1 in proteoliposomes.
abstract: KCNE1 is a single-transmembrane protein of the KCNE family that modulates the function of voltage-gated potassium channels, including KCNQ1. Hereditary mutations in KCNE1 have been linked to diseases such as long QT syndrome (LQTS), atrial fibrillation, sudden infant death syndrome, and deafness. The transmembrane domain (TMD) of KCNE1 plays a key role in mediating the physical association with KCNQ1 and in subsequent modulation of channel gating kinetics and conductance. However, the mechanisms associated with these roles for the TMD remain poorly understood, highlighting a need for experimental structural studies. A previous solution NMR study of KCNE1 in LMPG micelles revealed a curved transmembrane domain, a structural feature proposed to be critical to KCNE1 function. However, this curvature potentially reflects an artifact of working in detergent micelles. Double electron electron resonance (DEER) measurements were conducted on KCNE1 in LMPG micelles, POPC/POPG proteoliposomes, and POPC/POPG lipodisq nanoparticles to directly compare the structure of the TMD in a variety of different membrane environments. Experimentally derived DEER distances coupled with simulated annealing molecular dynamic simulations were used to probe the bilayer structure of the TMD of KCNE1. The results indicate that the structure is helical in proteoliposomes and is slightly curved, which is consistent with the previously determined solution NMR structure in micelles. The evident resilience of the curvature in the KCNE1 TMD leads us to hypothesize that the curvature is likely to be maintained upon binding of the protein to the KCNQ1 channel.
authors.affiliation: Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States.
authors.forename: Indra D
authors.initials: ID
authors.lastname: Sahu
authors.forename: Brett M
authors.initials: BM
authors.lastname: Kroncke
authors.forename: Rongfu
authors.initials: R
authors.lastname: Zhang
authors.forename: Megan M
authors.initials: MM
authors.lastname: Dunagan
authors.forename: Hubbell J
authors.initials: HJ
authors.lastname: Smith
authors.forename: Andrew
authors.initials: A
authors.lastname: Craig
authors.forename: Robert M
authors.initials: RM
authors.lastname: McCarrick
authors.forename: Charles R
authors.initials: CR
authors.lastname: Sanders
authors.forename: Gary A
authors.initials: GA
authors.lastname: Lorigan
mesh_terms: D019943:Amino Acid Substitution; D006801:Humans; D008051:Lipid Bilayers / Q000737:chemistry*; D008081:Liposomes / Q000737:chemistry; D056004:Molecular Dynamics Simulation; D010713:Phosphatidylcholines / Q000737:chemistry; D010715:Phosphatidylglycerols / Q000737:chemistry; D024642:Potassium Channels, Voltage-Gated / Q000737:chemistry* / Q000235:genetics; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D013816:Thermodynamics
chemical_list: C489622:KCNE1 protein, human; D008051:Lipid Bilayers; D008081:Liposomes; D010713:Phosphatidylcholines; D010715:Phosphatidylglycerols; D024642:Potassium Channels, Voltage-Gated; C060037:1-palmitoyl-2-oleoylglycero-3-phosphoglycerol; C028694:1-palmitoyl-2-oleoylphosphatidylcholine