title: Functional and transcript analysis of a novel metal transporter gene EpNramp from a dark septate endophyte (Exophiala pisciphila).
abstract: Various metal transporters mediate sub-cellular sequestration of diverse metal ions, contribute to cellular metal tolerance, and control metal partitioning, particularly under conditions of high rates of metal influx into organisms. In the current study, a ubiquitous and evolutionary conserved metal transporter gene, homology to natural resistance associated macrophage protein (Nramp), was cloned from a metal-tolerant isolate of dark septate endophyte (DSE, Exophiala pisciphila), and its functional and transcript characterization were analyzed. The full-length Nramp gene from E. pisciphila (named EpNramp) was 1716 bp and expected to encode a polypeptide of 571 amino acid residues. EpNramp fused to green fluorescent protein suggested that EpNramp was a plasma membrane metal transporter, which was consistent with the results of bioinformatics analysis with 11 transmembrane domains. Yeast functional complementation revealed that EpNramp could complement the growth defect of Fe-uptake yeast mutant (fet3fet4 double mutant) by mediating the transport of Fe(2+). Expression of EpNramp increased Cd(2+) sensitivity and Cd(2+) accumulation in yeast. In addition, qPCR data revealed that E. pisciphila significantly down-regulated EpNramp expression with elevated Cd(2+) exposure. Altogether, EpNramp is a bivalent cation transporter localized in cell membrane, which is necessary for efficient translocation of both Fe and Cd, and its activities partly attributed to the tolerance of DSE to toxic and excessive Cd(2+) supplements.
authors.affiliation: Key Laboratory of Conservation and Utilization for Bioresources and Key Laboratory of Microbial Diversity in Southwest China, Ministry of Education, Yunnan University, Kunming, 650091 Yunnan, PR China; Kunming Police Dog Base of the Ministry of Public Security, Kunming, 650204 Yunnan, PR China. Electronic address: 407574875@qq.cm.
authors.forename: Yun-Fang
authors.initials: YF
authors.lastname: Wei
authors.affiliation: Key Laboratory of Conservation and Utilization for Bioresources and Key Laboratory of Microbial Diversity in Southwest China, Ministry of Education, Yunnan University, Kunming, 650091 Yunnan, PR China. Electronic address: litao@ynu.edu.cn.
authors.forename: Tao
authors.initials: T
authors.lastname: Li
authors.affiliation: College of Food Science and Technology, Yunnan Agricultural University, Kunming, 650201 Yunnan, PR China. Electronic address: lilf@ynau.edu.cn.
authors.forename: Ling-Fei
authors.initials: LF
authors.lastname: Li
authors.affiliation: Key Laboratory of Conservation and Utilization for Bioresources and Key Laboratory of Microbial Diversity in Southwest China, Ministry of Education, Yunnan University, Kunming, 650091 Yunnan, PR China. Electronic address: 410068686@qq.com.
authors.forename: Jun-Ling
authors.initials: JL
authors.lastname: Wang
authors.affiliation: Key Laboratory of Conservation and Utilization for Bioresources and Key Laboratory of Microbial Diversity in Southwest China, Ministry of Education, Yunnan University, Kunming, 650091 Yunnan, PR China. Electronic address: 278342531@qq.com.
authors.forename: Guan-Hua
authors.initials: GH
authors.lastname: Cao
authors.affiliation: Key Laboratory of Conservation and Utilization for Bioresources and Key Laboratory of Microbial Diversity in Southwest China, Ministry of Education, Yunnan University, Kunming, 650091 Yunnan, PR China. Electronic address: zhaozhw@ynu.edu.cn.
authors.forename: Zhi-Wei
authors.initials: ZW
authors.lastname: Zhao
mesh_terms: D002104:Cadmium / Q000378:metabolism; D027682:Cation Transport Proteins / Q000235:genetics*; D060026:Endophytes / Q000235:genetics; D005093:Exophiala / Q000235:genetics* / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics*; D008670:Metals / Q000378:metabolism; D012441:Saccharomyces cerevisiae; D000099173:Natural Resistance-associated Macrophage Protein 1
chemical_list: D002104:Cadmium; D027682:Cation Transport Proteins; D005656:Fungal Proteins; D008670:Metals; D000099173:Natural Resistance-associated Macrophage Protein 1
keywords: Cadmium (Cd(2+)); Dark septate endophyte (DSE); Exophiala pisciphila; Metal transporter; Nramp