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A Cardiomyopathy Mutation in the Myosin Essential Light Chain Alters Actomyosin Structure.
- Source :
-
Biophysical journal [Biophys J] 2017 Jul 11; Vol. 113 (1), pp. 91-100. - Publication Year :
- 2017
-
Abstract
- We have used site-directed time-resolved fluorescence resonance energy transfer to determine the effect of a pathological mutation in the human ventricular essential light chain (hVELC) of myosin, on the structural dynamics of the actin-myosin complex. The hVELC modulates the function of actomyosin, through the interaction of its N-terminal extension with actin and its C-terminal lobe with the myosin heavy chain. Several mutations in hVELC are associated with hypertrophic cardiomyopathy (HCM). Some biochemical effects of these mutations are known, but further insight is needed about their effects on the structural dynamics of functioning actomyosin. Therefore, we introduced the HCM mutation E56G into a single-cysteine (C16) hVELC construct and substituted it for the VELC of bovine cardiac myosin subfragment 1. Using a donor fluorescent probe on actin (at C374) and an acceptor probe on C16 of hVELC, we performed time-resolved fluorescence resonance energy transfer, directly detecting structural changes within the bound actomyosin complex during function. The E56G mutation has no significant effect on actin-activated ATPase activity or actomyosin affinity in the presence of ATP, or on the structure of the strong-binding S complex in the absence of ATP. However, in the presence of saturating ATP, where both W (prepowerstroke) and S (postpowerstroke) structural states are observed, the mutant increases the mole fraction of the S complex (increasing the duty ratio), while shifting the structure of the remaining W complex toward that of S, indicating a structural redistribution toward the strongly bound (force-generating) complex. We propose that this effect is responsible for the hypercontractile phenotype induced by this HCM mutation in myosin.<br /> (Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.)
- Subjects :
- Actins chemistry
Actins metabolism
Actomyosin chemistry
Actomyosin genetics
Adenosine Triphosphatases metabolism
Adenosine Triphosphate chemistry
Adenosine Triphosphate metabolism
Animals
Cardiac Myosins chemistry
Cattle
Escherichia coli
Fluorescence Resonance Energy Transfer
Humans
Models, Molecular
Muscle, Skeletal chemistry
Muscle, Skeletal metabolism
Myosin Light Chains chemistry
Rabbits
Actomyosin metabolism
Cardiac Myosins genetics
Cardiac Myosins metabolism
Mutation
Myosin Light Chains genetics
Myosin Light Chains metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1542-0086
- Volume :
- 113
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- Biophysical journal
- Publication Type :
- Academic Journal
- Accession number :
- 28700929
- Full Text :
- https://doi.org/10.1016/j.bpj.2017.05.027