title: Molecular Cloning and Functional Analysis of a Na+-Insensitive K+Transporter ofCapsicum chinenseJacq.
abstract: 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 ofCcHAK1gene was isolated from roots of the habanero pepper (Capsicum chinense).CcHAK1expression 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 toCapsicum annuumCaHAK1 andSolanum lycopersicumLeHAK5. 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 Kmand Vmaxfor Rb of 50 μM and 0.52 nmol mg-1min-1, 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 inC. chinenseplants undergoing K+-deficiency and salt stress.
authors.affiliation: 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.
authors.forename: Nancy
authors.initials: N
authors.lastname: Ruiz-Lau
authors.affiliation: 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.
authors.forename: Emanuel
authors.initials: E
authors.lastname: Bojórquez-Quintal
authors.affiliation: Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid Madrid, Spain.
authors.forename: Begoña
authors.initials: B
authors.lastname: Benito
authors.affiliation: Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigación Científica de Yucatán Mérida, Mexico.
authors.forename: Ileana
authors.initials: I
authors.lastname: Echevarría-Machado
authors.affiliation: Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigación Científica de Yucatán Mérida, Mexico.
authors.forename: Lucila A
authors.initials: LA
authors.lastname: Sánchez-Cach
authors.affiliation: Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigación Científica de Yucatán Mérida, Mexico.
authors.forename: María de Fátima
authors.initials: MF
authors.lastname: Medina-Lara
authors.affiliation: Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigación Científica de Yucatán Mérida, Mexico.
authors.forename: Manuel
authors.initials: M
authors.lastname: Martínez-Estévez
keywords: Capsicum chinense; HAK-type transporter; K+-starvation; potassium; roots; sodium