6s5b
From Proteopedia
Non-square conformation of KtrA R16K mutant ring with bound ADP
Structural highlights
FunctionKTRA_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] Publication Abstract from PubMedRCK domains regulate the activity of K(+) channels and transporters in eukaryotic and prokaryotic organisms by responding to ions or nucleotides. The mechanisms of RCK activation by Ca(2+) in the eukaryotic BK and bacterial MthK K(+) channels are well understood. However, the molecular details of activation in nucleotide-dependent RCK domains are not clear. Through a functional and structural analysis of the mechanism of ATP activation in KtrA, a RCK domain from the B. subtilis KtrAB cation channel, we have found that activation by nucleotide requires binding of cations to an intra-dimer interface site in the RCK dimer. In particular, divalent cations are coordinated by the gamma-phosphates of bound-ATP, tethering the two subunits and stabilizing the active state conformation. Strikingly, the binding site residues are highly conserved in many different nucleotide-dependent RCK domains, indicating that divalent cations are a general cofactor in the regulatory mechanism of many nucleotide-dependent RCK domains. Activation of a nucleotide-dependent RCK domain requires binding of a cation cofactor to a conserved site.,Teixeira-Duarte CM, Fonseca F, Morais Cabral JH Elife. 2019 Dec 23;8. pii: 50661. doi: 10.7554/eLife.50661. PMID:31868587[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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