Deletion of a histidine-rich loop of AtMTP1, a vacuolar Zn(2+)/H(+) antiporter of Arabidopsis thaliana, stimulates the transport activity.

ABSTRACT: Arabidopsis thaliana AtMTP1 belongs to the cation diffusion facilitator family and is localized on the vacuolar membrane. We investigated the enzymatic kinetics of AtMTP1 by a heterologous expression system in the yeast Saccharomyces cerevisiae, which lacked genes for vacuolar membrane zinc transporters ZRC1 and COT1. The yeast mutant expressing AtMTP1 heterologously was tolerant to 10 mm ZnCl(2). Active transport of zinc into vacuoles of living yeast cells expressing AtMTP1 was confirmed by the fluorescent zinc indicator FuraZin-1. Zinc transport was quantitatively analyzed by using vacuolar membrane vesicles prepared from AtMTP1-expressing yeast cells and radioisotope (65)Zn(2+). Active zinc uptake depended on a pH gradient generated by endogenous vacuolar H(+)-ATPase. The activity was i

SUBMITTER: Kawachi M 

PROVIDER: S-EPMC2417167 | biostudies-literature | 2008 Mar

REPOSITORIES: biostudies-literature