Related Experiment Videos
Modeling study of human renal chloride channel (hCLC-5) mutations suggests a structural-functional relationship
Fiona Wu1, Philippe Roche, Paul T Christie
1Molecular Endocrinology Group, Nuffield Department of Clinical Medicine, University of Oxford, Botnar Research Centre, Nuffield Orthopaedic Centre, Headington, Oxford, United Kingdom.
Background:
Dent's disease, a renal tubular disorder characterized by low-molecular-weight proteinuria, hypercalciuria, and nephrolithiasis, is due to inactivating mutations in the X-linked renal-specific chloride channel, hCLC-5. The x-ray crystal structures of two bacterial chloride channels (CLCs) have recently been established, thereby allowing us to construct a model for hCLC-5 and further examine the role of its mutations.
Methods:
The data regarding 49 hCLC-5 mutations were reviewed. Thirty-four mutations that predicted absent or truncated channels were excluded. The remaining 15 mutations (one in-frame insertion and 14 missense mutations), 12 of which have been studied electrophysiologically, were assessed. The hCLC-5 sequence was aligned with the Salmonella typhimurium and Escherichia coli sequences and used to map the hCLC-5 mutations onto a three-dimensional model.
Results:
hCLC-5 is a homodimeric protein, with each subunit consisting of 18 helices. None of the missense mutations involved the chloride (Cl-) selectivity filter, but 12 of the 15 mutations were found to be clustered at the interface of the two subunits. Six of these mutations occurred in two of the helices that either form part of the interface or lie in close proximity to the interface, and three other mutations that did not lead to complete loss of Cl- conductance were at the edge of the interface.
Conclusion:
These results demonstrate a crucial role for the interaction between the two subunits at the interface of the homodimeric hCLC-5.
Insights
Mutations in the human chloride channel 5 (hCLC-5) cause Dent's disease. This study modeled hCLC-5, revealing mutations cluster at subunit interfaces, crucial for channel function.
Area of Science:
- Molecular biology
- Renal physiology
- Structural biology
Background:
- Dent's disease is a renal tubular disorder linked to mutations in the hCLC-5 chloride channel.
- Characterized by proteinuria, hypercalciuria, and kidney stones.
- Understanding hCLC-5 structure is key to understanding disease mechanisms.
Purpose of the Study:
- To model the human chloride channel 5 (hCLC-5) based on bacterial CLC structures.
- To analyze the impact of known Dent's disease mutations on hCLC-5 structure and function.
- To investigate the role of subunit interactions in hCLC-5 activity.
Main Methods:
- Reviewed 49 hCLC-5 mutations, focusing on 15 missense and in-frame insertion mutations.
- Aligned hCLC-5 sequence with bacterial CLC sequences.
- Mapped mutations onto a 3D model of hCLC-5.
Main Results:
- hCLC-5 functions as a homodimer, with each subunit comprising 18 helices.
- No disease-causing mutations affected the chloride (Cl-) selectivity filter.
- 12 of 15 mutations were located at the interface between the two subunits.
Conclusions:
- The interface between hCLC-5 subunits is critical for channel function.
- Mutations at this interface likely disrupt homodimerization and channel activity, leading to Dent's disease.
- Structural insights provide a basis for understanding disease pathogenesis.