期刊
JOURNAL OF MOLECULAR BIOLOGY
卷 430, 期 10, 页码 1459-1478出版社
ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD
DOI: 10.1016/j.jmb.2018.04.006
关键词
myosin; myopathy; muscle; coiled coil; mutations
资金
- MRC [MR/K001272/1]
- BHF [PG/15/2/31208]
- BBSRC [BB/M009114/1]
- WT ISSF award
- Wellcome Trust [WT094232]
- Zeiss LSM 880 inverted microscope [WT104918]
- Deltavision Deconvolution microscope [WT065321]
- BBSRC [BB/I007423/1, BB/M009114/1] Funding Source: UKRI
- MRC [MR/K001272/1] Funding Source: UKRI
Over 20 mutations in beta-cardiac myosin heavy chain (beta-MHC), expressed in cardiac and slow muscle fibers, cause Laing early-onset distal myopathy (MPD-1), a skeletal muscle myopathy. Most of these mutations are in the coiled-coil tail and commonly involve a mutation to a proline or a single-residue deletion, both of which are predicted to strongly affect the secondary structure of the coiled coil. To test this, we characterized the effects of two MPD-1 causing mutations: A1603P and K1617del in vitro and in cells. Both mutations affected secondary structure, decreasing the helical content of 15 heptad and light meromyosin constructs. Both mutations also severely disrupted the ability of glutathione S-transferase-light meromyosin fusion proteins to form minifilaments in vitro, as demonstrated by negative stain electron microscopy. Mutant eGFP-tagged beta-MHC accumulated abnormally into the M-line of sarcomeres in cultured skeletal muscle myotubes. Incorporation of eGFP-tagged beta-MHC into sarcomeres in adult rat cardiomyocytes was reduced. Molecular dynamics simulations using a composite structure of part of the coiled coil demonstrated that both mutations affected the structure, with the mutation to proline (A1603P) having a smaller effect compared to K1617del. Taken together, it seems likely that the MPD-1 mutations destabilize the coiled coil, resulting in aberrant myosin packing in thick filaments in muscle sarcomeres, providing a potential mechanism for the disease. (C) 2018 The Authors. Published by Elsevier Ltd.
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