Molecular effect of a novel missense mutation, L266V, on function of ClC-5 protein in a Japanese patient with Dent's disease.

We report the use of three-dimensional computational analysis of chloride channel 5 (ClC-5) based on a novel mutation, L266V, identified in a 15-year-old Japanese boy with Dent's disease. Since both leucine and valine are branched-chain amino acids, it has not been proved conclusively whether L266V mutation is actually responsible for the development of Dent's disease. In the present study using molecular analysis, we investigated the mechanism for loss of function of the ClC-5 protein resulting from the L266V mutation. Structural analysis of the normal ClC-5 transmembrane region using molecular modeling showed that the two respective Leu266 residues were located at the interface of the dimer formed by the aligned ClC-5 monomers. The Leu266 side-chains were positioned close to each other through hydrophobic interaction, resembling two interconnecting hooks. When Leu266 was replaced by a valine residue, the hydrophobic interaction between the CLC-5 monomers was reduced, and dimer formation was impaired. This computer simulation analysis has thus provided strong evidence for the important role of Leu266 in the dimerization of human ClC-5 in membranes. Conclusion: The findings of the present study suggest that computational modeling and molecular analysis could be an alternative to labor-intensive in vitro functional studies.