Structural highlights
Function[KTRA_BACSU] Catalytic subunit of the KtrAB potassium uptake transporter. The 2 major potassium transporter complexes KtrAB and KtrCD confer resistance to both suddenly imposed and prolonged osmotic stress.[1] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe regulation of cation content is critical for cell growth. However, the molecular mechanisms that gate the systems that control K+ movements remain unclear. KTN is a highly conserved cytoplasmic domain present ubiquitously in a variety of prokaryotic and eukaryotic K+ channels and transporters. Here we report crystal structures for two representative KTN domains that reveal a dimeric hinged assembly. Alternative ligands NAD+ and NADH block or vacate, respectively, the hinge region affecting the dimer's conformational flexibility. Conserved, surface-exposed hydrophobic patches that become coplanar upon hinge closure provide an assembly interface for KTN tetramerization. Mutational analysis using the KefC system demonstrates that this domain directly interacts with its respective transmembrane constituent, coupling ligand-mediated KTN conformational changes to the permease's activity. A mechanism of regulating transmembrane potassium flux through a ligand-mediated conformational switch.,Roosild TP, Miller S, Booth IR, Choe S Cell. 2002 Jun 14;109(6):781-91. PMID:12086676[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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