Journal article
Small-angle X-ray scattering of calpain-5 reveals a highly open conformation among calpains
Journal of structural biology, Vol.196(3), pp.309-318
12/2016
DOI: 10.1016/j.jsb.2016.07.017
PMCID: PMC5118095
PMID: 27474374
Abstract
Calpain-5 is a calcium-activated protease expressed in the retina. Mutations in calpain-5 cause autosomal dominant neovascular inflammatory vitreoretinopathy (ADNIV, OMIM#193235). The structure of calpain-5 has not been determined, thus hindering the investigation of its proteolytic targets and pathological role in ADNIV. Herein, we report models of the proteolytic core of calpain-5 (mini-calpain-5) containing two globular domains (termed DIIa-IIb) connected by a short, flexible linker, consistent with small-angle X-ray scattering (SAXS) data. Structural modeling in the absence of calcium suggests that mini-calpain-5 adopts a more open conformation when compared to previously determined structures of other calpain cores. This open conformation, achieved by a rotation of DIIa and DIIb with respect to each other, prevents formation of the active site and constrains the enzyme in an inactivated form. The relative domain rotation of 60–100° we found for mini-calpain-5 (a non-classical calpain) is significantly greater than the largest rotation previously observed for a classical calpain (i.e., 55.0° for mini-calpain-9). Together with our prediction that, in the full-length form, a long loop in DIIb (loop C1), a few residues downstream of the inter-domain linker, likely interacts with the shorter, acidic, inactivating loop on domain-III (DIII), these structural insights illuminate the complexity of calpain regulation. Moreover, our studies argue that pursuing higher resolution structural studies are necessary to understand the complex activity regulation prevalent in the calpain family and for the design of specific calpain inhibitors.
Details
- Title: Subtitle
- Small-angle X-ray scattering of calpain-5 reveals a highly open conformation among calpains
- Creators
- Lokesh Gakhar - Department of Biochemistry, University of Iowa, Iowa City, IA, USAAlexander G Bassuk - Department of Pediatrics, University of Iowa, Iowa City, IA, USAGabriel Velez - Omics Lab, University of Iowa, Iowa City, IA, USASaif Khan - Protein Crystallography Facility, University of Iowa, Iowa City, IA, USAJing Yang - Protein Crystallography Facility, University of Iowa, Iowa City, IA, USAStephen H Tsang - Barbara and Donald Jonas Laboratory of Stem Cells and Regenerative Medicine and Bernard & Shirlee Brown Glaucoma Laboratory, Edward S. Harkness Eye Institute, Columbia University, New York, NY, USAVinit B Mahajan - Omics Lab, University of Iowa, Iowa City, IA, USA
- Resource Type
- Journal article
- Publication Details
- Journal of structural biology, Vol.196(3), pp.309-318
- DOI
- 10.1016/j.jsb.2016.07.017
- PMID
- 27474374
- PMCID
- PMC5118095
- NLM abbreviation
- J Struct Biol
- ISSN
- 1047-8477
- eISSN
- 1095-8657
- Publisher
- Elsevier Inc
- Grant note
- DOI: 10.13039/100000002, name: National Institutes of Health, award: K08EY020530, R01EY016822, R01GM105404; DOI: 10.13039/100000862, name: Doris Duke Charitable Foundation, award: 2013103; DOI: 10.13039/100001818, name: Research to Prevent Blindness; DOI: 10.13039/100000002, name: NIH, award: T32GM007337; DOI: 10.13039/100006206, name: DOE Office of Biological and Environmental Research; DOI: 10.13039/100000002, name: National Institute of Health project MINOS
- Language
- English
- Date published
- 12/2016
- Academic Unit
- Neurology; Stead Family Department of Pediatrics; Iowa Neuroscience Institute; Biochemistry and Molecular Biology; Neurology (Pediatrics); Medicine Administration
- Record Identifier
- 9984020612302771
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