title: The KAC family of kinesin-like proteins is essential for the association of chloroplasts with the plasma membrane in land plants.
abstract: Chloroplasts require association with the plasma membrane for movement in response to light and for appropriate positioning within the cell to capture photosynthetic light efficiently. In Arabidopsis, CHLOROPLAST UNUSUAL POSITIONING 1 (CHUP1), KINESIN-LIKE PROTEIN FOR ACTIN-BASED CHLOROPLAST MOVEMENT 1 (KAC1) and KAC2 are required for both the proper movement of chloroplasts and the association of chloroplasts with the plasma membrane, through the reorganization of short actin filaments located on the periphery of the chloroplasts. Here, we show that KAC and CHUP1 orthologs (AcKAC1, AcCHUP1A and AcCHUP1B, and PpKAC1 and PpKAC2) play important roles in chloroplast positioning in the fern Adiantum capillus-veneris and the moss Physcomitrella patens. The knockdown of AcKAC1 and two AcCHUP1 genes induced the aggregation of chloroplasts around the nucleus. Analyses of A. capillus-veneris mutants containing perinuclear-aggregated chloroplasts confirmed that AcKAC1 is required for chloroplast-plasma membrane association. In addition, P. patens lines in which two KAC genes had been knocked out showed an aggregated chloroplast phenotype similar to that of the fern kac1 mutants. These results indicate that chloroplast positioning and movement are mediated through the activities of KAC and CHUP1 proteins, which are conserved in land plants.
authors.affiliation: Department of Biology, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581 Japan.
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Suetsugu
authors.forename: Yoshikatsu
authors.initials: Y
authors.lastname: Sato
authors.forename: Hidenori
authors.initials: H
authors.lastname: Tsuboi
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kasahara
authors.forename: Takato
authors.initials: T
authors.lastname: Imaizumi
authors.forename: Takatoshi
authors.initials: T
authors.lastname: Kagawa
authors.forename: Yuji
authors.initials: Y
authors.lastname: Hiwatashi
authors.forename: Mitsuyasu
authors.initials: M
authors.lastname: Hasebe
authors.forename: Masamitsu
authors.initials: M
authors.lastname: Wada
mesh_terms: D008841:Actin Cytoskeleton / Q000235:genetics / Q000378:metabolism; D035681:Adiantum / Q000033:anatomy & histology / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D060365:Chloroplast Proteins / Q000235:genetics / Q000378:metabolism*; D002736:Chloroplasts / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D055786:Gene Knockout Techniques; D020868:Gene Silencing; D017343:Genes, Plant; D005816:Genetic Complementation Test; D016547:Kinesins / Q000235:genetics / Q000378:metabolism*; D018515:Plant Leaves / Q000033:anatomy & histology / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism
chemical_list: D060365:Chloroplast Proteins; D010940:Plant Proteins; D016547:Kinesins