Journal article
Biochemical properties of V91G calmodulin: A calmodulin point mutation that deregulates muscle contraction in Drosophila
Protein science, Vol.13(12), pp.3285-3297
12/2004
DOI: 10.1110/ps.04928204
PMCID: PMC2287309
PMID: 15557269
Abstract
A mutation (
Cam
7
) to the single endogenous calmodulin gene of
Drosophila
generates a mutant protein with valine 91 changed to glycine (V91G D-CaM). This mutation produces a unique pupal lethal phenotype distinct from that of a null mutation. Genetic studies indicate that the phenotype reflects deregulation of calcium fluxes within the larval muscles, leading to hypercontraction followed by muscle failure. We investigated the biochemical properties of V91G D-CaM. The effects of the mutation on free CaM are minor: Calcium binding, and overall secondary and tertiary structure are indistinguishable from those of wild type. A slight destabilization of the C-terminal domain is detectable in the calcium-free (apo-) form, and the calcium-bound (holo-) form has a somewhat lower surface hydrophobicity. These findings reinforce the indications from the in vivo work that interaction with a specific CaM target(s) underlies the mutant defects. In particular, defective regulation of ryanodine receptor (RyR) channels was indicated by genetic interaction analysis. Studies described here establish that the putative CaM binding region of the
Drosophila
RyR (D-RyR) binds wild-type D-CaM comparably to the equivalent CaM-RyR interactions seen for the mammalian skeletal muscle RyR channel isoform (RYR1). The V91G mutation weakens the interaction of both apo- and holo-D-CaM with this binding region, and decreases the enhancement of the calcium-binding affinity of CaM that is detectable in the presence of the RyR target peptide. The predicted functional consequences of these changes are consonant with the in vivo phenotype, and indicate that D-RyR is one, if not the major, target affected by the V91G mutation in CaM.
Details
- Title: Subtitle
- Biochemical properties of V91G calmodulin: A calmodulin point mutation that deregulates muscle contraction in Drosophila
- Creators
- Bo Wang - Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77005, USAStephen R Martin - Division of Physical Biochemistry, National Institute for Medical Research, London NW7 1AA, United KingdomRhonda A Newman - Department of Biochemistry, University of Iowa, Roy J. and Lucille A. Carver College of Medicine, Iowa City, Iowa 52242-1109, USASusan L Hamilton - Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas 77030, USAMadeline A Shea - Department of Biochemistry, University of Iowa, Roy J. and Lucille A. Carver College of Medicine, Iowa City, Iowa 52242-1109, USAPeter M Bayley - Division of Physical Biochemistry, National Institute for Medical Research, London NW7 1AA, United KingdomKathleen M Beckingham - Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77005, USA
- Resource Type
- Journal article
- Publication Details
- Protein science, Vol.13(12), pp.3285-3297
- Publisher
- Cold Spring Harbor Laboratory Press
- DOI
- 10.1110/ps.04928204
- PMID
- 15557269
- PMCID
- PMC2287309
- ISSN
- 0961-8368
- eISSN
- 1469-896X
- Language
- English
- Date published
- 12/2004
- Academic Unit
- Molecular Physiology and Biophysics; Iowa Neuroscience Institute; Biochemistry and Molecular Biology
- Record Identifier
- 9984024538102771
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