Activation of a nucleotide-dependent RCK domain requires binding of a cation cofactor to a conserved site
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Portugal
Abstract
RCK 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 Ca2+ 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 γ-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.
Data availability
Diffraction data have been deposited in PDB under the accession code 6S2J, 6S5B, 6S5D, 6S7R, 6S5N, 6S5O, 6S5E, 6S5G,6S5C.Source data files have been provided for Figures 6, 7, 8 and 9.
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Square conformation of KtrA R16K mutant ring with bound ATPProtein Data Bank, 6S2J.
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Non-square conformation of KtrA R16K mutant ring with bound ADPProtein Data Bank, 6S5B.
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Square conformation of KtrA R16A mutant ring with bound ATPProtein Data Bank, 6S5D.
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Non-square conformations of KtrA R16A mutant rings with bound ADPProtein Data Bank, 6S7R.
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Non-square conformations of KtrA E125Q mutant rings with bound ATPProtein Data Bank, 6S5N.
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Non-square conformations of KtrA E125Q mutant rings with bound ADPProtein Data Bank, 6S5O.
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Non-square conformation of KtrA A80P mutant ring with bound ATPProtein Data Bank, 6S5E.
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Non-square conformation of KtrA A80P mutant ring with bound ADPProtein Data Bank, 6S5G.
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Square conformation of KtrA WT ring with bound ATP and calciumProtein Data Bank, 6S5C.
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Square-shaped octameric structure of KtrA with ATP boundProtein Data Bank, 4J90.
Article and author information
Author details
Celso M Teixeira-Duarte
João H Morais Cabral
Funding
Fundação Luso-Americana para o Desenvolvimento (FLAD Life Science 2020)
- João H Morais Cabral
Fundação para a Ciência e a Tecnologia (POCI-01-0145-FEDER-029863 (PTDC/BIA-BQM/29863/2017))
- João H Morais Cabral
Fundação para a Ciência e a Tecnologia (POCI-01-0145-FEDER-007274)
- João H Morais Cabral
Fundação para a Ciência e a Tecnologia (SFRH/BD/123761/2016)
- Celso M Teixeira-Duarte
Fundação para a Ciência e a Tecnologia (SFRH/BPD/102753/2014)
- Fátima Fonseca
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2019, Teixeira-Duarte et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Activation of a nucleotide-dependent RCK domain requires binding of a cation cofactor to a conserved site
eLife 8:e50661.
https://doi.org/10.7554/eLife.50661
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