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J Biol Chem. 2011 Feb 25;286(8):6733-41. doi: 10.1074/jbc.M110.175877. Epub 2010 Dec 20.

ATP induces conformational changes in the carboxyl-terminal region of ClC-5.

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1
Programme of Molecular Structure and Function, Research Institute, the Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada.

Abstract

ATP binding enhances the activity of ClC-5, the transporter mutated in Dent disease, a disease affecting the renal proximal tubule. Previously, the ATP binding site was revealed in x-ray crystal structures of the cytoplasmic region of this membrane protein. Disruption of this site by mutagenesis (Y617A-ClC-5) reduced the functional expression and ATP-dependent regulation of the full-length transporter in Xenopus oocytes. However, insight into the conformational changes underlying ATP-dependent regulation is lacking. Here, we show that ATP binding induces a change in protein conformation. Specifically, small angle x-ray scattering experiments indicate that ATP binding promotes a clamp-like closure of the isolated ClC-5 carboxyl-terminal region. Limited proteolysis studies show that ATP binding induces conformational compaction of the carboxyl-terminal region in the intact membrane protein as well. In the context of fibroblasts and proximal tubule epithelial cells, disruption of the ATP binding site in full-length ClC-5 (Y617A-ClC-5) led to a defect in processing and trafficking out of the endoplasmic reticulum. These latter findings account for the decrease in functional expression previously reported for this ATP-binding mutant and prompt future study of a model whereby conformational compaction caused by ATP binding promotes biosynthetic maturation.

PMID:
21173145
PMCID:
PMC3057859
DOI:
10.1074/jbc.M110.175877
[Indexed for MEDLINE]
Free PMC Article
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