Myosin XI-I is mechanically and enzymatically unique among class-xi myosins in arabidopsis

Takeshi Haraguchi, Motoki Tominaga, Akihiko Nakano, Keiichi Yamamoto, Kohji Ito

    Research output: Contribution to journalArticle

    7 Citations (Scopus)

    Abstract

    Arabidopsis possesses 13 genes encoding class-XI myosins. Among these, myosin XI-I is phylogenetically distant. To examine the molecular properties of Arabidopsis thaliana myosin XI-I (At myosin XI-I), we performed in vitro mechanical and enzymatic analyses using recombinant constructs of At myosin XI-I. Unlike other biochemically studied class-XI myosins, At myosin XI-I showed extremely low actinactivated ATPase activity (Vmax = 3.7 Pi s1 head1). The actin-sliding velocity of At myosin XI-I was 0.25 mm s1, >10 times lower than those of other class-XI myosins. The ADP dissociation rate from acto-At myosin XI-I was 17 s1, accounting for the low actin-sliding velocity. In contrast, the apparent affinity for actin in the presence of ATP, estimated from Kapp (0.61 mM) of actin-activated ATPase, was extremely high. The equilibrium dissociation constant for actin was very low in both the presence and absence of ATP, indicating a high affinity for actin. To examine At myosin XI-I motility in vivo, green fluorescent protein-fused full-length At myosin XI-I was expressed in cultured Arabidopsis cells. At myosin XI-I localized not only on the nuclear envelope but also on small dots moving slowly (0.23 mm s1) along actin filaments. Our results show that the properties of At myosin XI-I differ from those of other Arabidopsis class-XI myosins. The data suggest that At myosin XI-I does not function as a driving force for cytoplasmic streaming but regulates the organelle velocity, supports processive organelle movement or acts as a tension generator.

    Original languageEnglish
    Pages (from-to)1732-1743
    Number of pages12
    JournalPlant and Cell Physiology
    Volume57
    Issue number8
    DOIs
    Publication statusPublished - 2016 Aug 1

    Keywords

    • Actin
    • Arabidopsis
    • ATPase
    • Kinetics
    • Molecular motor
    • Myosin

    ASJC Scopus subject areas

    • Medicine(all)
    • Physiology
    • Plant Science
    • Cell Biology

    Fingerprint Dive into the research topics of 'Myosin XI-I is mechanically and enzymatically unique among class-xi myosins in arabidopsis'. Together they form a unique fingerprint.

  • Cite this