title: Functional characterization of a potassium transporter gene NrHAK1 in Nicotiana rustica.
abstract: The purpose of this study is to investigate the function of a novel potassium transporter gene (NrHAK1) isolated from Nicotiana rustica roots using yeast complement and real-time PCR technique. The complementary DNA (cDNA) of NrHAK1, 2 488 bp long, contains an open reading frame (ORF) of 2 334 bp encoding a protein of 777 amino acids (87.6 kDa) with 12 predicted transmembrane domains. The NrHAK1 protein shows a high sequence similarity to those of high-affinity potassium transporters in Mesembryanthemum, Phytolacca acinosa, Arabidopsis thaliana, and so on. We found that the NrHAK1 gene could complement the yeast-mutant defect in K+ uptake. Among several tissues surveyed, the expression level of NrHAK1 was most abundant in the root tip and was up-regulated when exposed to potassium starvation. Moreover, the transcript accumulation was significantly reduced by adding 5 mmol/L NH4+ to the solution. These results suggest that NrHAK1 plays an important role in potassium absorption in N. rustica.
authors.affiliation: Department of Life Sciences and Engineering, Harbin Institute of Technology, Harbin 150001, China.
authors.forename: Zhao-kui
authors.initials: ZK
authors.lastname: Guo
authors.forename: Qian
authors.initials: Q
authors.lastname: Yang
authors.forename: Xiu-qing
authors.initials: XQ
authors.lastname: Wan
authors.forename: Pei-qiang
authors.initials: PQ
authors.lastname: Yan
mesh_terms: D027682:Cation Transport Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D011188:Potassium / Q000378:metabolism*; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology; D012964:Sodium / Q000494:pharmacology; D014026:Nicotiana / Q000235:genetics* / Q000378:metabolism
chemical_list: D027682:Cation Transport Proteins; C110543:HAK1 protein, plant; D010940:Plant Proteins; D000644:Quaternary Ammonium Compounds; D012964:Sodium; D011188:Potassium