Calcium-induced mechanical change in the neck domain alters the activity of plant myosin XI

Motoki Tominaga, Hiroaki Kojima, Etsuo Yokota, Rinna Nakamori, Michael Anson, Teruo Shimmen, Kazuhiro Oiwa*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

35 Citations (Scopus)


Plant myosin XI functions as a motor that generates cytoplasmic streaming in plant cells. Although cytoplasmic streaming is known to be regulated by intracellular Ca2+ concentration, the molecular mechanism underlying this control is not fully understood. Here, we investigated the mechanism of regulation of myosin XI by Ca2+ at the molecular level. Actin filaments were easily detached from myosin XI in an in vitro motility assay at high Ca2+ concentration (pCa 4) concomitant with the detachment of calmodulin light chains from the neck domains. Electron microscopic observations showed that myosin XI at pCa 4 shortened the neck domain by 30%. Single-molecule analysis revealed that the step size of myosin XI at pCa 4 was shortened to 27 nm under low load and to 22 nm under high load compared with 35 nm independent of the load for intact myosin XI. These results indicate that modulation of the mechanical properties of the neck domain is a key factor for achieving the Ca2+-induced regulation of cytoplasmic streaming.

Original languageEnglish
Pages (from-to)30711-30718
Number of pages8
JournalJournal of Biological Chemistry
Issue number36
Publication statusPublished - 2012 Aug 31
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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