title: Distinct Biochemical Properties of Arabidopsis thaliana Actin Isoforms.
abstract: Plants and animals express multiple actin isoforms in a manner that is dependent on tissues, organs and the stage of development. Previous genetic analyses suggested that individual actin isoforms have specific roles in cells, but there is little biochemical evidence to support this hypothesis. In this study, we purified four recombinant Arabidopsis actin isoforms, two major vegetative actin isoforms, ACT2 and ACT7, and two major reproductive isoforms, ACT1 and ACT11, and characterized them biochemically. Phalloidin bound normally to the filaments of the two reproductive actins as well as to the filaments of skeletal muscle actin. However, phalloidin bound only weakly to ACT7 filaments and hardly at all to ACT2 filaments, despite the conserved sequence of the phalloidin-binding site. Polymerization and phosphate release rates among these four actin isoforms were also significantly different. Moreover, interactions with profilin (PRF) were also different among the four Arabidopsis actin isoforms. PRF1 and PRF2 inhibited the polymerization of ACT1, ACT11 and ACT7, while ACT2 was only weakly affected. Plant actin isoforms have different biochemical properties. This result supports the idea that actin isoforms play specific roles to achieve multiple cell functions.
authors.affiliation: Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki, 305-8562 Japan Graduate School of Life and Environmental Sciences, University of Tsukuba, Ibaraki, 305-8572 Japan.
authors.forename: Saku T
authors.initials: ST
authors.lastname: Kijima
authors.affiliation: Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki, 305-8562 Japan Graduate School of Life and Environmental Sciences, University of Tsukuba, Ibaraki, 305-8572 Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Hirose
authors.affiliation: Department of Biology, Faculty of Sciences, Kyushu University, Fukuoka, 812-8581 Japan Present address: Division of Structural Biology, Medical Institute of Bioregulation, Kyushu University, Fukuoka, 812-8582 Japan and Research Center for Live-Protein Dynamics, Kyushu University, Fukuoka, 812-8582 Japan.
authors.forename: Sam-Geun
authors.initials: SG
authors.lastname: Kong
authors.affiliation: Department of Biology, Faculty of Sciences, Kyushu University, Fukuoka, 812-8581 Japan Pesent address: Department of Biological Sciences, Graduate School of Science and Engineering, Tokyo Metropolitan University, Tokyo, 192-0397 Japan.
authors.forename: Masamitsu
authors.initials: M
authors.lastname: Wada
authors.affiliation: Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki, 305-8562 Japan Graduate School of Life and Environmental Sciences, University of Tsukuba, Ibaraki, 305-8572 Japan t-uyeda@aist.go.jp.
authors.forename: Taro Q P
authors.initials: TQ
authors.lastname: Uyeda
mesh_terms: D008841:Actin Cytoskeleton / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D000199:Actins / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D017124:Conserved Sequence; D003599:Cytoskeleton / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism; D030821:Plants, Genetically Modified; D058105:Polymerization; D051304:Profilins / Q000235:genetics / Q000378:metabolism; D020033:Protein Isoforms
chemical_list: C480844:ACT7 protein, Arabidopsis; D000199:Actins; D029681:Arabidopsis Proteins; C495746:PRF1 protein, Arabidopsis; C495747:PRF2 protein, Arabidopsis; D010710:Phosphates; D051304:Profilins; D020033:Protein Isoforms; C076846:ACT2 protein, Arabidopsis
keywords: Actin; Arabidopsis thaliana; Isoform; Phalloidin; Profilin