title: ZIP genes encode proteins involved in membrane trafficking of the TGN-PVC/vacuoles.
abstract: The Arabidopsis zigzgag (zig) is a loss-of-function mutant of Qb-SNARE VTI11 which is involved in vesicle trafficking between the trans-Golgi network (TGN) and vacuoles. zig-1 exhibits abnormality in both shoot gravitropism and morphology. To elucidate the molecular network of the post-Golgi membrane trafficking in plant cells, we have isolated the suppressor mutants of zig. Here we report zig suppressor 2 (zip2) and zip4 that are recessive mutants and partially suppress abnormality in both gravitropism and morphology. ZIP2 encodes AtVPS41/AtVAM2 protein that is thought to be an Arabidopsis ortholog of yeast Vps41p/Vam2p, which is involved in protein sorting to vacuoles as a subunit of the tethering complex HOPS. Yeast Vps41p is also proposed to function in budding of adaptor protein (AP)-3-coated vesicles from the Golgi. The zip2 mutation is a missense mutation in a conserved amino acid of a putative clathrin heavy chain repeat (CHCR) domain. AtVPS41 is a single-copy gene in the Arabidopsis genome and the T-DNA insertion mutant appears to be lethal, whereas the zip2 single mutant showed no obvious phenotype. On the other hand, zip4 is a loss-of-function mutant of a putative ortholog of the yeast AP-3 mu subunit. In addition, loss-of-function mutants of other subunits of AP-3, ap-3beta and ap-3delta, also exhibit a suppressive effect on the zig-1 phenotype. Although these genes are also single-copy genes in the genome, the loss-of-function mutants of AP-3 grow normally. Our results suggest that AtVPS41 and AP-3 play roles in the proper function of the post-Golgi trafficking network and support membrane trafficking to vacuoles.
authors.affiliation: Plant Genetics Laboratory, National Institute of Genetics, Mishima, Shizuoka, 411-8540, Japan.
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Niihama
authors.forename: Noriko
authors.initials: N
authors.lastname: Takemoto
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Hashiguchi
authors.forename: Masao
authors.initials: M
authors.lastname: Tasaka
authors.forename: Miyo Terao
authors.initials: MT
authors.lastname: Morita
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000235:genetics; D026161:MADS Domain Proteins / Q000235:genetics / Q000378:metabolism*; D016254:Mutagenesis, Insertional; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport; D018749:RNA, Plant / Q000235:genetics; D014617:Vacuoles / Q000378:metabolism*; D033921:Vesicular Transport Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: C101342:APETALA 3 protein, Arabidopsis; D029681:Arabidopsis Proteins; D004269:DNA, Bacterial; D026161:MADS Domain Proteins; D018749:RNA, Plant; C036483:T-DNA; D033921:Vesicular Transport Proteins