Cryo-EM structure of the lysosomal chloride-proton exchanger CLC-7 in complex with OSTM1
- Memorial Sloan Kettering Cancer Center, United States
Abstract
The chloride-proton exchanger CLC-7 plays critical roles in lysosomal homeostasis and bone regeneration and its mutation can lead to osteopetrosis, lysosomal storage disease and neurological disorders. In lysosomes and the ruffled border of osteoclasts, CLC-7 requires a b-subunit, OSTM1, for stability and activity. Here we present electron cryomicroscopy structures of CLC-7 in occluded states by itself and in complex with OSTM1, determined at resolutions up to 2.8 Å. In the complex, the luminal surface of CLC-7 is entirely covered by a dimer of the heavily glycosylated and disulfide-bonded OSTM1, which serves to protect CLC-7 from the degradative environment of the lysosomal lumen. OSTM1 binding does not induce large-scale rearrangements of CLC-7, but does have minor effects the conformation of the ion-conduction pathway, potentially contributing to its regulatory role. These studies provide insights into the role of OSTM1 and serve as a foundation for understanding the mechanisms of CLC-7 regulation.
Data availability
Cryo-EM maps and atomic coordinates have been deposited with the EMDB and PDB under accession codes EMD-22386 and PDB ID 7JM6 for ggCLC-7 and EMD-22389 andPDB ID 7JM7 for human CLC-7/OSTM1. All other reagents are available from the corresponding author upon reasonable request.
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Structure of human CLC-7 in complex with OSTM1RCSB Protein Data Bank, 7JM7.
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Structure of chicken CLC-7Electron Microscopy Data Bank, EMD-22386.
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Structure of human CLC-7 in complex with OSTM1Electron Microscopy Data Bank, EMD-22389.
Article and author information
Author details
Funding
Searle Scholars Program
- Richard K Hite
Josie Robertson Investigators Program
- Richard K Hite
National Cancer Institute (accessory subunit)
- Richard K Hite
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2020, Schrecker et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Cryo-EM structure of the lysosomal chloride-proton exchanger CLC-7 in complex with OSTM1
eLife 9:e59555.
https://doi.org/10.7554/eLife.59555
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