https://eutils.ncbi.nlm.nih.gov/entrez/eutils/efetch.fcgi?db=pubmed&id=31980523&retmode=xml&tool=Litmetric&email=readroberts32@gmail.com&api_key=61f08fa0b96a73de8c900d749fcb997acc09 319805232020052720200615
1091-649011762020Feb11Proceedings of the National Academy of Sciences of the United States of AmericaProc Natl Acad Sci U S AConformational changes upon gating of KirBac1.1 into an open-activated state revealed by solid-state NMR and functional assays.293829472938-294710.1073/pnas.1915010117The conformational changes required for activation and K+ conduction in inward-rectifier K+ (Kir) channels are still debated. These structural changes are brought about by lipid binding. It is unclear how this process relates to fast gating or if the intracellular and extracellular regions of the protein are coupled. Here, we examine the structural details of KirBac1.1 reconstituted into both POPC and an activating lipid mixture of 3:2 POPC:POPG (wt/wt). KirBac1.1 is a prokaryotic Kir channel that shares homology with human Kir channels. We establish that KirBac1.1 is in a constitutively active state in POPC:POPG bilayers through the use of real-time fluorescence quenching assays and Förster resonance energy transfer (FRET) distance measurements. Multidimensional solid-state NMR (SSNMR) spectroscopy experiments reveal two different conformers within the transmembrane regions of the protein in this activating lipid environment, which are distinct from the conformation of the channel in POPC bilayers. The differences between these three distinct channel states highlight conformational changes associated with an open activation gate and suggest a unique allosteric pathway that ties the selectivity filter to the activation gate through interactions between both transmembrane helices, the turret, selectivity filter loop, and the pore helix. We also identify specific residues involved in this conformational exchange that are highly conserved among human Kir channels.Copyright © 2020 the Author(s). Published by PNAS.AmaniRezaRDepartment of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409.BorcikCollin GCGDepartment of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409.KhanNazmul HNHDepartment of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409.VersteegDerek BDBDepartment of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409.YekefallahMaryamMDepartment of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409.DoHoa QHQDepartment of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409.CoatsHeather RHRDepartment of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409.WylieBenjamin JBJ0000-0001-8183-2762Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409 benjamin.j.wylie@ttu.edu.engR35 GM124979GMNIGMS NIH HHSUnited StatesJournal ArticleResearch Support, N.I.H., ExtramuralResearch Support, Non-U.S. Gov't20200124
United StatesProc Natl Acad Sci U S A75058760027-84240Bacterial Proteins0KCNJ1 protein, human0Phosphatidylcholines0Phosphatidylglycerols0Potassium Channels, Inwardly Rectifying81490-05-31-palmitoyl-2-oleoylglycero-3-phosphoglycerolRWP5GA015DPotassiumTE895536Y51-palmitoyl-2-oleoylphosphatidylcholineIMBacterial ProteinschemistrygeneticsmetabolismCatalytic DomainFluorescence Resonance Energy TransferKineticsMagnetic Resonance SpectroscopyModels, MolecularPhosphatidylcholineschemistrymetabolismPhosphatidylglycerolschemistrymetabolismPotassiummetabolismPotassium Channels, Inwardly RectifyingchemistrygeneticsmetabolismProtein ConformationProtein DomainsProtein Structure, Secondaryallosterylipid activationmembrane proteinpotassium channelsolid-state NMRThe authors declare no competing interest.2020126602020528602020126602020124ppublish31980523PMC702217810.1073/pnas.19150101171915010117Clarke O. 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