Ruiz-Lau Nancy, Bojórquez-Quintal Emanuel, Benito Begoña, Echevarría-Machado Ileana, Sánchez-Cach Lucila A, Medina-Lara María de Fátima, Martínez-Estévez Manuel
Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigación Científica de YucatánMérida, Mexico; CONACYT, Instituto Tecnológico Nacional de México, Instituto Tecnológico de Tuxtla GutiérrezTuxtla Gutiérrez, Mexico.
Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigación Científica de YucatánMérida, Mexico; CONACYT, Laboratorio de Análisis y Diagnóstico del Patrimonio, Colegio de MichoacánZamora, Mexico.
Front Plant Sci. 2016 Dec 27;7:1980. doi: 10.3389/fpls.2016.01980. eCollection 2016.
High-affinity K (HAK) transporters are encoded by a large family of genes and are ubiquitous in the plant kingdom. These HAK-type transporters participate in low- and high-affinity potassium (K) uptake and are crucial for the maintenance of K homeostasis under hostile conditions. In this study, the full-length cDNA of gene was isolated from roots of the habanero pepper (). expression was positively regulated by K starvation in roots and was not inhibited in the presence of NaCl. Phylogenetic analysis placed the CcHAK1 transporter in group I of the HAK K transporters, showing that it is closely related to CaHAK1 and LeHAK5. Characterization of the protein in a yeast mutant deficient in high-affinity K uptake (WΔ3) suggested that CcHAK1 function is associated with high-affinity K uptake, with K and V for Rb of 50 μM and 0.52 nmol mg min, respectively. K uptake in yeast expressing the CcHAK1 transporter was inhibited by millimolar concentrations of the cations ammonium ([Formula: see text]) and cesium (Cs) but not by sodium (Na). The results presented in this study suggest that the CcHAK1 transporter may contribute to the maintenance of K homeostasis in root cells in plants undergoing K-deficiency and salt stress.
高亲和性钾（HAK）转运蛋白由一个庞大的基因家族编码，在植物界广泛存在。这些HAK型转运蛋白参与低亲和性和高亲和性钾（K）的吸收，对于在恶劣条件下维持钾稳态至关重要。在本研究中，从哈瓦那辣椒（）的根中分离出基因的全长cDNA。根中CcHAK1的表达受钾饥饿正向调控，且在有NaCl存在时不被抑制。系统发育分析将CcHAK1转运蛋白置于HAK钾转运蛋白的第一组，表明它与CaHAK1和LeHAK5密切相关。在缺乏高亲和性钾吸收的酵母突变体（WΔ3）中对该蛋白的表征表明，CcHAK1的功能与高亲和性钾吸收相关，其对钾的亲和力（K）和铷对铯的转运速率（V）分别为50 μM和0.52 nmol mg min。表达CcHAK1转运蛋白的酵母中的钾吸收受到毫摩尔浓度的阳离子铵（[化学式：见正文]）和铯（Cs）的抑制，但不受钠（Na）的抑制。本研究结果表明，CcHAK1转运蛋白可能有助于在经历钾缺乏和盐胁迫的植物的根细胞中维持钾稳态。
