Abstract
Rice lip19 that encodes a bZIP protein of 148 amino acids has been isolated as one of low-temperature-induced genes. Hence LIP19 seems to play a regulatory role in gene expression during cold stress, although the details of its function remain to be discovered. Since LIP19 lacks the common ability of bZIP transcription factors to homodimerize and to bind DNA we searched for other putative partners for heterodimerization. A screening for clone(s) whose product interacts with the LIP19 protein using a yeast two-hybrid system disclosed OsOBF1.
Here we confirmed the interaction between LIP19 and OsOBF1 using a pull-down assay. An experiment of domain-swapping between LIP19 and OsOBF1 revealed that a leucine-zipper portion of LIP19 caused the defect in homodimerization. With in situ hybridization, we showed that lip19 and OsOBF1 are expressed at similar sites. Based on the data, we will discuss a role of LIP19 in cold signaling pathway in rice.
