Publication Date:
2013-11-26
Description:
Voltage-gated calcium (CaV) channels catalyse rapid, highly selective influx of Ca(2+) into cells despite a 70-fold higher extracellular concentration of Na(+). How CaV channels solve this fundamental biophysical problem remains unclear. Here we report physiological and crystallographic analyses of a calcium selectivity filter constructed in the homotetrameric bacterial NaV channel NaVAb. Our results reveal interactions of hydrated Ca(2+) with two high-affinity Ca(2+)-binding sites followed by a third lower-affinity site that would coordinate Ca(2+) as it moves inward. At the selectivity filter entry, Site 1 is formed by four carboxyl side chains, which have a critical role in determining Ca(2+) selectivity. Four carboxyls plus four backbone carbonyls form Site 2, which is targeted by the blocking cations Cd(2+) and Mn(2+), with single occupancy. The lower-affinity Site 3 is formed by four backbone carbonyls alone, which mediate exit into the central cavity. This pore architecture suggests a conduction pathway involving transitions between two main states with one or two hydrated Ca(2+) ions bound in the selectivity filter and supports a 'knock-off' mechanism of ion permeation through a stepwise-binding process. The multi-ion selectivity filter of our CaVAb model establishes a structural framework for understanding the mechanisms of ion selectivity and conductance by vertebrate CaV channels.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3877713/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉 〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3877713/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Tang, Lin -- Gamal El-Din, Tamer M -- Payandeh, Jian -- Martinez, Gilbert Q -- Heard, Teresa M -- Scheuer, Todd -- Zheng, Ning -- Catterall, William A -- R01 HL112808/HL/NHLBI NIH HHS/ -- R01 HL117896/HL/NHLBI NIH HHS/ -- R01 NS015751/NS/NINDS NIH HHS/ -- R01HL112808/HL/NHLBI NIH HHS/ -- R01NS015751/NS/NINDS NIH HHS/ -- T32 GM008268/GM/NIGMS NIH HHS/ -- T32GM008268/GM/NIGMS NIH HHS/ -- Howard Hughes Medical Institute/ -- England -- Nature. 2014 Jan 2;505(7481):56-61. doi: 10.1038/nature12775. Epub 2013 Nov 24.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉1] Department of Pharmacology, University of Washington, Seattle, Washington 98195, USA [2] Howard Hughes Medical Institute, University of Washington, Seattle, Washington 98195, USA [3]. ; 1] Department of Pharmacology, University of Washington, Seattle, Washington 98195, USA [2]. ; 1] Department of Pharmacology, University of Washington, Seattle, Washington 98195, USA [2] Department of Structural Biology, Genentech Inc., South San Francisco, California 94080, USA. ; Department of Pharmacology, University of Washington, Seattle, Washington 98195, USA. ; 1] Department of Pharmacology, University of Washington, Seattle, Washington 98195, USA [2] Howard Hughes Medical Institute, University of Washington, Seattle, Washington 98195, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24270805" target="_blank"〉PubMed〈/a〉
Keywords:
Bacterial Proteins/*chemistry/genetics/*metabolism
;
Binding Sites
;
Biocatalysis
;
Calcium/metabolism
;
Calcium Channels/*chemistry/genetics/*metabolism
;
Cations, Divalent/metabolism
;
Crystallography, X-Ray
;
Electric Conductivity
;
*Ion Channel Gating
;
Models, Biological
;
Models, Molecular
;
Structure-Activity Relationship
;
Substrate Specificity
Print ISSN:
0028-0836
Electronic ISSN:
1476-4687
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
,
Natural Sciences in General
,
Physics
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