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Functional analysis of the rice vacuolar zinc transporter OsMTP1

Functional analysis of the rice vacuolar zinc transporter OsMTP1
Functional analysis of the rice vacuolar zinc transporter OsMTP1
Heavy metal homeostasis is maintained in plant cells by specialized transporters which compartmentalize or efflux metal ions, maintaining cytosolic concentrations within a narrow range. OsMTP1 is a member of the cation diffusion facilitator (CDF)/metal tolerance protein (MTP) family of metal cation transporters in Oryza sativa, which is closely related to Arabidopsis thaliana MTP1. Functional complementation of the Arabidopsis T-DNA insertion mutant mtp1-1 demonstrates that OsMTP1 transports Zn in planta and localizes at the tonoplast. When heterologously expressed in the yeast mutant zrc1 cot1, OsMTP1 complemented its Zn hypersensitivity and was also localized to the vacuole. OsMTP1 alleviated, to some extent, the Co sensitivity of this mutant, rescued the Fe hypersensitivity of the ccc1 mutant at low Fe concentrations, and restored growth of the Cd-hypersensitive mutant ycf1 at low Cd concentrations. These results suggest that OsMTP1 transports Zn but also Co, Fe, and Cd, possibly with lower affinity. Site-directed mutagenesis studies revealed two substitutions in OsMTP1 that alter the transport function of this protein. OsMTP1 harbouring a substitution of Leu82 to a phenylalanine can still transport low levels of Zn, with an enhanced affinity for Fe and Co, and a gain of function for Mn. A substitution of His90 with an aspartic acid completely abolishes Zn transport but improves Fe transport in OsMTP1. These amino acid residues are important in determining substrate specificity and may be a starting point for refining transporter activity in possible biotechnological applications, such as biofortification and phytoremediation.
0022-0957
2871-2883
Menguer, Paloma K.
55a81fc7-e27b-430a-893f-de6ad1163cc7
Farthing, Emily
6c75eb33-eed1-4470-8dc2-bb76add7089b
Peaston, Kerry A.
55c75e49-e55d-441c-a07e-867e1fa000e7
Ricachenevsky, Felipe Klein
2f1fcb1a-2cdd-418c-bb74-e2bce78b9282
Fett, Janette Palma
e031c1ac-fbe8-4488-b2f9-8dddd935ead1
Williams, Lorraine E.
79ee1856-3732-492b-8ac5-239749c85d9e
Menguer, Paloma K.
55a81fc7-e27b-430a-893f-de6ad1163cc7
Farthing, Emily
6c75eb33-eed1-4470-8dc2-bb76add7089b
Peaston, Kerry A.
55c75e49-e55d-441c-a07e-867e1fa000e7
Ricachenevsky, Felipe Klein
2f1fcb1a-2cdd-418c-bb74-e2bce78b9282
Fett, Janette Palma
e031c1ac-fbe8-4488-b2f9-8dddd935ead1
Williams, Lorraine E.
79ee1856-3732-492b-8ac5-239749c85d9e

Menguer, Paloma K., Farthing, Emily, Peaston, Kerry A., Ricachenevsky, Felipe Klein, Fett, Janette Palma and Williams, Lorraine E. (2013) Functional analysis of the rice vacuolar zinc transporter OsMTP1. Journal of Experimental Botany, 64 (10), 2871-2883. (doi:10.1093/jxb/ert136).

Record type: Article

Abstract

Heavy metal homeostasis is maintained in plant cells by specialized transporters which compartmentalize or efflux metal ions, maintaining cytosolic concentrations within a narrow range. OsMTP1 is a member of the cation diffusion facilitator (CDF)/metal tolerance protein (MTP) family of metal cation transporters in Oryza sativa, which is closely related to Arabidopsis thaliana MTP1. Functional complementation of the Arabidopsis T-DNA insertion mutant mtp1-1 demonstrates that OsMTP1 transports Zn in planta and localizes at the tonoplast. When heterologously expressed in the yeast mutant zrc1 cot1, OsMTP1 complemented its Zn hypersensitivity and was also localized to the vacuole. OsMTP1 alleviated, to some extent, the Co sensitivity of this mutant, rescued the Fe hypersensitivity of the ccc1 mutant at low Fe concentrations, and restored growth of the Cd-hypersensitive mutant ycf1 at low Cd concentrations. These results suggest that OsMTP1 transports Zn but also Co, Fe, and Cd, possibly with lower affinity. Site-directed mutagenesis studies revealed two substitutions in OsMTP1 that alter the transport function of this protein. OsMTP1 harbouring a substitution of Leu82 to a phenylalanine can still transport low levels of Zn, with an enhanced affinity for Fe and Co, and a gain of function for Mn. A substitution of His90 with an aspartic acid completely abolishes Zn transport but improves Fe transport in OsMTP1. These amino acid residues are important in determining substrate specificity and may be a starting point for refining transporter activity in possible biotechnological applications, such as biofortification and phytoremediation.

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Published date: 12 June 2013
Organisations: Chemistry, Environmental

Identifiers

Local EPrints ID: 353694
URI: http://eprints.soton.ac.uk/id/eprint/353694
ISSN: 0022-0957
PURE UUID: 6fe23787-d8a6-4968-be68-3dd61d4a3fea

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Date deposited: 14 Jun 2013 10:20
Last modified: 16 Jul 2019 21:31

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Contributors

Author: Paloma K. Menguer
Author: Emily Farthing
Author: Kerry A. Peaston
Author: Felipe Klein Ricachenevsky
Author: Janette Palma Fett

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