An Arabidopsis thaliana high-affinity molybdate transporter required for efficient uptake of molybdate from soil

*Biotechnology Research Center and
^†Graduate School of Agricultural and Life Sciences, University of Tokyo, Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan;
^§RIKEN Plant Science Center, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan;
^¶Department of Plant Biology, Carnegie Institution of Washington, 260 Panama Street, Palo Alto, CA 94305; and
^‖Solution-Oriented Research for Science and Technology (SORST), Japan Science and Technology Corporation, Cho-ku, Tokyo 103-0027, Japan

Edited by Maarten J. Chrispeels, University of California at San Diego, La Jolla, CA, and approved October 1, 2007 (received for review July 7, 2007)

Abstract

Molybdenum (Mo) is a trace element essential for living organisms, however no molybdate transporter has been identified in eukaryotes. Here, we report the identification of a molybdate transporter, MOT1, from Arabidopsis thaliana. MOT1 is expressed in both roots and shoots, and the MOT1 protein is localized, in part, to plasma membranes and to vesicles. MOT1 is required for efficient uptake and translocation of molybdate and for normal growth under conditions of limited molybdate supply. Kinetics studies in yeast revealed that the K _m value of MOT1 for molybdate is ≈20 nM. Furthermore, Mo uptake by MOT1 in yeast was not affected by coexistent sulfate, and MOT1 did not complement a sulfate transporter-deficient yeast mutant strain. These data confirmed that MOT1 is specific for molybdate and that the high affinity of MOT1 allows plants to obtain scarce Mo from soil.

Footnotes

**To whom correspondence should be addressed. E-mail: atorufu{at}mail.ecc.u-tokyo.ac.jp
Author contributions: H. Tomatsu, J.T., and T.F. designed research; H. Tomatsu, J.T., H. Takahashi, A.W.-T., and T.F. performed research; N.S. contributed new reagents/analytic tools; H. Tomatsu, J.T., and T.F. analyzed data; and H. Tomatsu, J.T., and T.F. wrote the paper.
↵ ^‡Present address: Department of Nutritional Science, University of Wisconsin, 1415 Linden Drive, Madison, WI 53706.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
This article contains supporting information online at www.pnas.org/cgi/content/full/0706373104/DC1.