Actin-binding domain of Rng2 sparsely bound on F-actin strongly inhibits actin movement on myosin II

Yuuki Hayakawa, Masak Takaine, Kien Xuan Ngo, Taiga Imai, Masafumi D. Yamada, Arash Badami Behjat, Kenichi Umeda, Keiko Hirose, Ayhan Yurtsever, Noriyuki Kodera, Kiyotaka Tokuraku, Osamu Numata, Takeshi Fukuma, Toshio Ando, Kentaro Nakano, Taro Qp Uyeda

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)


We report a case in which sub-stoichiometric binding of an actin-binding protein has profound structural and functional consequences, providing an insight into the fundamental properties of actin regulation. Rng2 is an IQGAP contained in contractile rings in the fission yeast Schizosaccharomyces pombe Here, we used high-speed atomic force microscopy and electron microscopy and found that sub-stoichiometric binding of the calponin-homology actin-binding domain of Rng2 (Rng2CHD) induces global structural changes in skeletal muscle actin filaments, including shortening of the filament helical pitch. Sub-stoichiometric binding of Rng2CHD also reduced the affinity between actin filaments and muscle myosin II carrying ADP and strongly inhibited the motility of actin filaments on myosin II in vitro. On skeletal muscle myosin II-coated surfaces, Rng2CHD stopped the actin movements at a binding ratio of 11%. Rng2CHD also inhibited actin movements on myosin II of the amoeba Dictyostelium, but in this case, by detaching actin filaments from myosin II-coated surfaces. Thus, sparsely bound Rng2CHD induces apparently cooperative structural changes in actin filaments and inhibits force generation by actomyosin II.

Original languageEnglish
JournalLife Science Alliance
Issue number1
Publication statusPublished - 2023 Jan 1

ASJC Scopus subject areas

  • Ecology
  • Biochemistry, Genetics and Molecular Biology (miscellaneous)
  • Plant Science
  • Health, Toxicology and Mutagenesis


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