GmZIP1 encodes a symbiosis-specific zinc transporter in soybean.
The importance of zinc in organisms is clearly established, and mechanisms involved in zinc acquisition by plants have recently received increased interest. In this report, the identification, characterization and location of GmZIP1, the first soybean member of the ZIP family of metal transporters, are described. GmZIP1 was found to possess eight putative transmembrane domains together with a histidine-rich extra-membrane loop. By functional complementation of zrt1zrt2 yeast cells no longer able to take up zinc, GmZIP1 was found to be highly selective for zinc, with an estimated K(m) value of 13.8 microm. Cadmium was the only other metal tested able to inhibit zinc uptake in yeast. An antibody raised against GmZIP1 specifically localized the protein to the peribacteroid membrane, an endosymbiotic membrane in nodules resulting from the interaction of the plant with its microsymbiont. The specific expression of GmZIP1 in nodules was confirmed by Northern blot, with no expression in roots, stems, or leaves of nodulated soybean plants. Antibodies to GmZIP1 inhibited zinc uptake by symbiosomes, indicating that at least some of the zinc uptake observed in isolated symbiosomes could be attributed to GmZIP1. The orientation of the protein in the membrane and its possible role in the symbiosis are discussed.
Moreau
Sophie
S
Laboratoire de Biologie Végétale et Microbiologie, CNRS FRE 2294, Université de Nice-Sophia Antipolis, Parc Valrose, 06108 Nice cédex 2, France.
Thomson
Rowena M
RM
Kaiser
Brent N
BN
Trevaskis
Ben
B
Guerinot
Mary Lou
ML
Udvardi
Michael K
MK
Puppo
Alain
A
Day
David A
DA
D000595:Amino Acid Sequence; D001692:Biological Transport; D015152:Blotting, Northern; D015139:Blotting, Southern; D002104:Cadmium / Q000378:metabolism; D002352:Carrier Proteins / Q000096:biosynthesis* / Q000737:chemistry* / Q000494:pharmacology; D027682:Cation Transport Proteins; D002462:Cell Membrane / Q000378:metabolism; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005816:Genetic Complementation Test; D007700:Kinetics; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000737:chemistry* / Q000494:pharmacology; D008969:Molecular Sequence Data; D005810:Multigene Family; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D030262:Soybean Proteins; D013025:Glycine max / Q000378:metabolism*; D013559:Symbiosis; D013997:Time Factors; D015032:Zinc / Q000737:chemistry*; D016335:Zinc Fingers
D002352:Carrier Proteins; D027682:Cation Transport Proteins; D018076:DNA, Complementary; D008565:Membrane Proteins; D030262:Soybean Proteins; C449800:ZIP1 protein, Glycine max; D002104:Cadmium; D015032:Zinc