Evidence against essential roles for subdomain 1 of actin in actomyosin sliding movements

Md Shahjahan P Siddique, Takashi Miyazaki, Eisaku Katayama, Taro Q P Uyeda, Makoto Suzuki

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)


We have engineered acto-S1chimera proteins carrying the entire actin inserted in loop 2 of the motor domain of Dictyostelium myosin II with 24 or 18 residue-linkers (CP24 and CP18, respectively). These proteins were capable of self-polymerization as well as copolymerization with skeletal actin and exhibited rigor-like structures. The MgATPase rate of CP24-skeletal actin copolymer was 1.06 s-1, which is slightly less than the V max of Dictyostelium S1. Homopolymer filaments of skeletal actin, CP24, and CP18 moved at 4.7 ± 0.6, 2.9 ± 0.6, and 4.1 ± 0.8 μm/s (mean ± SD), respectively, on coverslips coated with skeletal myosin at 27°C. Statistically thermodynamic considerations suggest that the S1 portion of chimera protein mostly resides on subdomain 1 (SD-1) of the actin portion even in the presence of ATP. This and the fact that filaments of CP18 with shorter linkers moved faster than CP24 filaments suggest that SD-1 might not be as essential as conventionally presumed for actomyosin sliding interactions.

Original languageEnglish
Pages (from-to)474-481
Number of pages8
JournalBiochemical and Biophysical Research Communications
Issue number2
Publication statusPublished - 2005 Jul 1


  • Acto-S1 chimera
  • ATPase
  • Dictyostelium
  • Electron microscopy
  • Intermediate state
  • Loop 2
  • Motility function

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology


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