Journal article
Structural kinetics of cardiac troponin C mutants linked to familial hypertrophic and dilated cardiomyopathy in troponin complexes
The Journal of biological chemistry, Vol.283(6), pp.3424-3432
02/08/2008
Handle:
https://hdl.handle.net/2376/109476
PMID: 18063575
Abstract
The key events in regulating cardiac muscle contraction involve Ca(2+) binding to and release from cTnC (troponin C) and structural changes in cTnC and other thin filament proteins triggered by Ca(2+) movement. Single mutations L29Q and G159D in human cTnC have been reported to associate with familial hypertrophic and dilated cardiomyopathy, respectively. We have examined the effects of these individual mutations on structural transitions in the regulatory N-domain of cTnC triggered by Ca(2+) binding and dissociation. This study was carried out with a double mutant or triple mutants of cTnC, reconstituted into troponin with tryptophanless cTnI and cTnT. The double mutant, cTnC(L12W/N51C) labeled with 1,5-IAEDANS at Cys-51, served as a control to monitor Ca(2+)-induced opening and closing of the N-domain by Förster resonance energy transfer (FRET). The triple mutants contained both L12W and N51C labeled with 1,5-IAEDANS, and either L29Q or G159D. Both mutations had minimal effects on the equilibrium distance between Trp-12 and Cys-51-AEDANS in the absence or presence of bound Ca(2+). L29Q had no effect on the closing rate of the N-domain triggered by release of Ca(2+), but reduced the Ca(2+)-induced opening rate. G159D reduced both the closing and opening rates. Previous results showed that the closing rate of cTnC N-domain triggered by Ca(2+) dissociation was substantially enhanced by PKA phosphorylation of cTnI. This rate enhancement was abolished by L29Q or G159D. These mutations alter the kinetics of structural transitions in the regulatory N-domain of cTnC that are involved in either activation (L29Q) or deactivation (G159D). Both mutations appear to be antagonistic toward phosphorylation signaling between cTnI and cTnC.
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Details
- Title
- Structural kinetics of cardiac troponin C mutants linked to familial hypertrophic and dilated cardiomyopathy in troponin complexes
- Creators
- Wen-Ji Dong - School of Chemical Engineering and Bioengineering, Washington State University, Pullman, Washington 99164; Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology, Washington State University, Pullman, Washington 99164. Electronic address: wdong@vetmed.wsu.eduJun Xing - Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Alabama 35294Yexin Ouyang - Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology, Washington State University, Pullman, Washington 99164Jianli An - Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Alabama 35294Herbert C Cheung - Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Alabama 35294
- Publication Details
- The Journal of biological chemistry, Vol.283(6), pp.3424-3432
- Academic Unit
- Chemical Engineering and Bioengineering, School of
- Publisher
- United States
- Grant note
- HL80186 / NHLBI NIH HHS HL52508 / NHLBI NIH HHS R01 HL080186 / NHLBI NIH HHS
- Identifiers
- 99900547357601842
- Language
- English
- Resource Type
- Journal article