LOW-TEMPERATURE-DEPENDENT EXPRESSION OF A RICE GENE ENCODING A PROTEIN WITH A LEUCINE-ZIPPER MOTIF

We have isolated from rice suspension cells three non-sequence-related cDNAs the expression of which is markedly induced by low, non-freezin g temperature. Here we further characterize one of the cDNA clones, li p19. Expression of lip19 is positively regulated by low temperature, b ut not affected by high (40-degrees-C) temperature. Sequencing and pri mer extension analyses showed that lip19 has a long (552 bp) 5' non-co ding sequence followed by a single open reading frame specifying a pro tein of 148 amino acids. The deduced amino acid sequence of the protei n, Lip19, shows at its amino-terminus a conserved basic region followe d by a ''leucine-zipper'' domain. The reported sequence most similar t o Lip19 is maize OCSBF-1, which is a bZip-type DNA binding protein. Th e possibility is suggested that Lip19 is a transcriptional factor that is positively controlled by low temperature.