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Mg 2+ -ATP Sensing in CNNM, a Putative Magnesium Transporter.
- Source :
-
Structure (London, England : 1993) [Structure] 2020 Mar 03; Vol. 28 (3), pp. 324-335.e4. Date of Electronic Publication: 2019 Dec 18. - Publication Year :
- 2020
-
Abstract
- The family of cystathionine-β-synthase (CBS)-pair domain divalent metal cation transport mediators (CNNMs) is composed of four integral membrane proteins associated with Mg <superscript>2+</superscript> transport. Structurally, CNNMs contain large cytosolic regions composed of a CBS-pair and a cyclic nucleotide-binding homology (CNBH) domain. How these regulate Mg <superscript>2+</superscript> transport activity is unknown. Here, we determined the crystal structures of cytosolic fragments in two conformations: Mg <superscript>2+</superscript> -ATP-analog bound and ligand free. The structures reveal open and closed conformations with functionally important contacts not observed in structures of the individual domains. We also identified a second Mg <superscript>2+</superscript> -binding region in the CBS-pair domain and a different dimerization interface for the CNBH domain. Analytical ultracentrifugation and isothermal titration calorimetry experiments revealed a tight correlation between Mg <superscript>2+</superscript> -ATP binding and protein dimerization. Mutations that blocked either function prevented cellular Mg <superscript>2+</superscript> efflux activity. The results suggest Mg <superscript>2+</superscript> efflux is regulated by conformational changes associated with Mg <superscript>2+</superscript> -ATP binding to CNNM CBS-pair domains.<br />Competing Interests: Declaration of Interests The authors declare no conflict of interest.<br /> (Copyright © 2019 Elsevier Ltd. All rights reserved.)
- Subjects :
- Animals
Binding Sites
Biological Transport
Cation Transport Proteins genetics
Crystallography, X-Ray
Cytosol metabolism
Humans
Models, Molecular
Mutation
Protein Conformation
Protein Domains
Protein Multimerization
Cation Transport Proteins chemistry
Cation Transport Proteins metabolism
Magnesium metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1878-4186
- Volume :
- 28
- Issue :
- 3
- Database :
- MEDLINE
- Journal :
- Structure (London, England : 1993)
- Publication Type :
- Academic Journal
- Accession number :
- 31864811
- Full Text :
- https://doi.org/10.1016/j.str.2019.11.016