Search

Using a degenerative probe designed according to the most conservative region of a known Lys- and His-specific amino acid transporter (LHT1) fromArabidopsis, we isolated a full-length cDNA namedOxHT(histidine transporter ofOryza sativaL.) by screening the rice cDNA library. The cDNA is 1.3 kb in length and the open reading frame encodes for a 441 amino acid protein with a calculated molecular mass of 49 kDa. Multiple sequence alignments showed thatOsHTshares a high degree of sequence conservation at the deduced amino acid level with theArabidopsisLHT1 and six putative lysine and histidine transporters. Computational analysis indicated thatOsHTis an integral membrane protein with 11 putative transmembrane helices. This was confirmed by the transient expression assay because theOsHT-GFPfusion protein was, indeed, localized mainly in the plasma membrane of onion epidermal cells. Functional complementation experiments demonstrated thatOsHT wasable to work as a histidine transporter inSaccharomyces cerevisiae, suggesting thatOsHTis a gene that encodes for a histidine transporter from rice. This is the first time that an LHT-type amino acid transporter gene has been cloned from higher plants other thanArabidopsis. [ABSTRACT FROM AUTHOR]