TcOPT3, a member of oligopeptide transporters from the hyperaccumulator Thlaspi caerulescens, is a novel Fe/Zn/Cd/Cu transporter.

Yi Ting Hu,Shao Jian Zheng,Gui Xin Li,Chun Yan Xu,Wei Wei Chen,Jian Li Yang,Jing Ying Yan,Feng Ming,Zheng Yu Xu,Sunghun Park

doi:10.1371/journal.pone.0038535

Abstract

Background Thlaspi caerulescens is a natural selected heavy metal hyperaccumulator that can not only tolerate but also accumulate extremely high levels of heavy metals in the shoots. Thus, to identify the transportors involved in metal long-distance transportation is very important for understanding the mechanism of heavy metal accumulation in this hyperaccumulator.Methodology/Principal FindingsWe cloned and characterized a novel gene TcOPT3 of OPT family from T. caerulescens. TcOPT3 was pronouncedly expressed in aerial parts, including stem and leaf. Moreover, in situ hybridization analyses showed that TcOPT3 expressed in the plant vascular systems, especially in the pericycle cells that may be involved in the long-distance transportation. The expression of TcOPT3 was highly induced by iron (Fe) and zinc (Zn) deficiency, especially in the stem and leaf. Sub-cellular localization showed that TcOPT3 was a plasma membrane-localized protein. Furthermore, heterogonous expression of TcOPT3 by mutant yeast (Saccharomyces cerevisiae) complementation experiments demonstrated that TcOPT3 could transport Fe2+ and Zn2+. Moreover, expression of TcOPT3 in yeast increased metal (Fe, Zn, Cu and Cd) accumulation and resulted in an increased sensitivity to cadmium (Cd) and copper (Cu).ConclusionsOur data demonstrated that TcOPT3 might encode an Fe/Zn/Cd/Cu influx transporter with broad-substrate. This is the first report showing that TcOPT3 may be involved in metal long-distance transportation and contribute to the heavy metal hyperaccumulation.

Highlights

Metal hyperaccumulators can tolerate high concentration of heavy metals in the soils and take them up actively and accumulate and distribute them to appropriate tissues at extreme high levels, make them very attractive for the remediation of heavy metal polluted soils [1]
Our data demonstrated that TcOPT3 might encode an Fe/Zn/Cd/Cu influx transporter with broad-substrate
This is the first report showing that TcOPT3 may be involved in metal long-distance transportation and contribute to the heavy metal hyperaccumulation

Summary

Introduction

Metal hyperaccumulators can tolerate high concentration of heavy metals in the soils and take them up actively and accumulate and distribute them to appropriate tissues at extreme high levels, make them very attractive for the remediation of heavy metal polluted soils [1]. A large amount of different metal hyperaccumulators have been recognized in different regions all over the world [2], among them, Thlaspi caerulescens, a Cd/Zn/Ni hyperaccumulator, has been used as a model plant to study the physiological and molecular mechanisms of heavy metal hyperaccumulation [3,4]. Inorganic nutrients and transit metals have been reported as the substrates of peptide transporters in the recent studies. Thlaspi caerulescens is a natural selected heavy metal hyperaccumulator that can tolerate and accumulate extremely high levels of heavy metals in the shoots. To identify the transportors involved in metal longdistance transportation is very important for understanding the mechanism of heavy metal accumulation in this hyperaccumulator

Methods

Results

Conclusion