RRC ID 30786
Author Haraguchi T, Tominaga M, Matsumoto R, Sato K, Nakano A, Yamamoto K, Ito K.
Title Molecular characterization and subcellular localization of Arabidopsis class VIII myosin, ATM1.
Journal J Biol Chem
Abstract Land plants possess myosin classes VIII and XI. Although some information is available on the molecular properties of class XI myosins, class VIII myosins are not characterized. Here, we report the first analysis of the enzymatic properties of class VIII myosin. The motor domain of Arabidopsis class VIII myosin, ATM1 (ATM1-MD), and the motor domain plus one IQ motif (ATM1-1IQ) were expressed in a baculovirus system and characterized. ATM1-MD and ATM1-1IQ had low actin-activated Mg(2+)-ATPase activity (Vmax = 4 s(-1)), although their affinities for actin were high (Kactin = 4 μM). The actin-sliding velocities of ATM1-MD and ATM1-1IQ were 0.02 and 0.089 μm/s, respectively, from which the value for full-length ATM1 is calculated to be ∼0.2 μm/s. The results of actin co-sedimentation assay showed that the duty ratio of ATM1 was ∼90%. ADP dissociation from the actin·ATM1 complex (acto-ATM1) was extremely slow, which accounts for the low actin-sliding velocity, low actin-activated ATPase activity, and high duty ratio. The rate of ADP dissociation from acto-ATM1 was markedly biphasic with fast and slow phase rates (5.1 and 0.41 s(-1), respectively). Physiological concentrations of free Mg(2+) modulated actin-sliding velocity and actin-activated ATPase activity by changing the rate of ADP dissociation from acto-ATM1. GFP-fused full-length ATM1 expressed in Arabidopsis was localized to plasmodesmata, plastids, newly formed cell walls, and actin filaments at the cell cortex. Our results suggest that ATM1 functions as a tension sensor/generator at the cell cortex and other structures in Arabidopsis.
Volume 289(18)
Pages 12343-55
Published 2014-5-2
DOI 10.1074/jbc.M113.521716
PII S0021-9258(20)41426-7
PMID 24637024
PMC PMC4007431
MeSH Actin Cytoskeleton / drug effects Actin Cytoskeleton / metabolism* Actins / metabolism Adenosine Diphosphate / metabolism Adenosine Triphosphatases / genetics Adenosine Triphosphatases / metabolism Adenosine Triphosphate / metabolism Arabidopsis / cytology Arabidopsis / genetics Arabidopsis / metabolism* Arabidopsis Proteins / genetics Arabidopsis Proteins / metabolism* Dinitrobenzenes / pharmacology Green Fluorescent Proteins / genetics Green Fluorescent Proteins / metabolism Kinetics Microscopy, Confocal Myosins / genetics Myosins / metabolism* Plants, Genetically Modified Protein Binding Protoplasts / cytology Protoplasts / metabolism Sulfanilamides / pharmacology Tubulin Modulators / pharmacology
IF 4.238
Times Cited 23
Arabidopsis / Cultured plant cells, genes pda07134