Calcium-mediated regulation of recombinant hybrids of full-length Physarum myosin heavy chain with Physarum/scallop myosin light chains

Ying Zhang,  Hozumi Kawamichi,  Kazuhiro Kohama and  Akio Nakamura

Department of Molecular Physiology and Medical Bioregulation, Yamaguchi University Graduate School of Medicine, Ube, Yamaguchi 755-8505, Japan  

Acta Biochim Biophys Sin 2016, 48: 536–543; doi: 10.1093/abbs/gmw031

Physarum myosin is a Ca2+-binding protein and its activity is inhibited by Ca2+. In the present study, to clarify the light chains (LCs) from the different species (Physarum and scallop) and to determine the specific Ca2+-regulated effects, we constructed hybrid myosins with a Physarum myosin heavy chain (Ph·HC) and Physarum and/or scallop myosin LCs, and examined Ca2+-mediated regulation of ATPases and motor activities. In these experiments, it was found that Ca2+ inhibited motilities and ATPase activities of Physarum hybrid myosin with scallop regulatory light chain (ScRLC) and Physarum essential light chain (PhELC) but could not inhibit those of the Physarum hybrid myosin mutant Ph·HC/ScRLC/PhELC-3A which lacks Ca2+-binding ability, indicating that PhELC plays a critical role in Ca2+-mediated regulation of Physarum myosin. Furthermore, the effects of Ca2+ on ATPase activities of Physarum myosin constructs are in the following order: Ph·HC/PhRLC/PhELC > Ph·HC/ScRLC/PhELC > Ph·HC/PhRLC/ScELC > Ph·HC/ScRLC/ScELC, suggesting that the presence of PhRLC and PhELC leads to the greatest Ca2+ sensitivity of Physarum myosin. Although we did not observe the motilities of Physarum hybrid myosin Ph·HC/PhRLC/ScELC and Ph·HC/ScRLC/ScELC, our results suggest that Ca2+-binding to the PhELC may alter the flexibility of the regulatory domain and induce a ’closed’ state, which may consequently prevent full activity and force generation.

Schematic diagram and purification of Physarum myosin hybrid constructs

阅读全文: http://www.abbs.org.cn/arts.asp?id=4021

相关论文: