A high molecular mass zinc transporter MTP12 forms a functional heteromeric complex with MTP5 in the Golgi in Arabidopsis thaliana.
Zinc (Zn) is an essential micronutrient required for plant growth and development. In Arabidopsis thaliana, several families of Zn transporters engaged in Zn import, export and intracellular compartmentalization play important roles in Zn homeostasis. We describe a novel Zn transporter, A. thaliana metal tolerance protein 12 (AtMTP12), which belongs to the cation diffusion facilitator family. AtMTP12 is predicted to consist of 798 amino acids and have 14 transmembrane segments. The expression of AtMTP12 in suspension-cultured cells was not affected by Zn deficiency or excess. Heterologous expression in a mutant of budding yeast (Saccharomyces cerevisiae) that lacks Msc2p, an orthologue of AtMTP12, revealed that AtMTP12 complements the growth phenotype of the msc2 mutant when AtMTP5t1, one of the splicing variants of AtMTP5, is coexpressed. Transient expression of AtMTP12-fused green fluorescent protein in A. thaliana mesophyll protoplasts demonstrated that AtMTP12 is localized to the Golgi apparatus. Moreover, AtMTP12 and AtMTP5t1 interact in the Golgi, as determined by a bimolecular fluorescence complementation assay. These results suggest that AtMTP12 forms a functional complex with AtMTP5t1 to transport Zn into the Golgi.


METHODS
Nucleotide sequence data for full-length of AtMTP12 is available in the DDBJ/EMBL/GenBank database under accession number AB986563.
Laboratory of Cell Dynamics, Graduate School of Bioagricultural Sciences, Nagoya University, Japan.
Takashi
T
Fujiwara
Laboratory of Cell Dynamics, Graduate School of Bioagricultural Sciences, Nagoya University, Japan.
Miki
M
Kawachi
Laboratory of Cell Dynamics, Graduate School of Bioagricultural Sciences, Nagoya University, Japan.
Yori
Y
Sato
Laboratory of Cell Dynamics, Graduate School of Bioagricultural Sciences, Nagoya University, Japan.
Haruki
H
Mori
Department of Integrated Biosciences, The University of Tokyo, Japan.|LPixel Inc., Bunkyo-ku, Japan.
Natsumaro
N
Kutsuna
Department of Integrated Biosciences, The University of Tokyo, Japan.
Seiichiro
S
Hasezawa
Laboratory of Cell Dynamics, Graduate School of Bioagricultural Sciences, Nagoya University, Japan.
Masayoshi
M
Maeshima
D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism*; D008970:Molecular Weight; D011485:Protein Binding
D029681:Arabidopsis Proteins
Arabidopsis; Golgi; MTP; cation diffusion facilitator; zinc