Cloning And Characterization Of A Rice DEAD-box RNA Helicase Gene, OsBIRH1

DEAD-box RNA helicase plays an important role in RNA metabolism, it is required for RNA synthesize to RNA degrade. DEAD-box protein may also control plant growth and development, disease resistance. In this study, we cloned and identified a novel rice DEAD-box RNA helicase gene, OsBIRH1. The full-length cDNA of OsBIRHl consists of 2167 bp in size, containing an open reading frame of 1926 bp, which predicts to encode a protein of 641 amino acids with calculated molecular weight of 70.8 kDa. The OsBIRHl gene is located on chromosome 3 of the rice genome and consists of 8 exons and 7 introns. The OsBIRHl protein contains conserved DEAD and HELICc domains, which are characteristics of the DEAD-box RNA helicases, and conserved motifs. Phylogenetic tree analysis revealed that OsBIRHl shows a high level of identity to an Arabidopsis DEAD-box RNA helicase and a human DEAD-box RNA helicase, giving 47%~54% identity at the amino acid sequence level.To better understand the biochemical activity of OsBIRHl protein, the OsBIRHl coding region was cloned into a prokaryytoic expression vector pRSET-A, and recombiant protein was purified. After induction by IPTG, recombinant OsBIRHl protein was purified using Ni-NTA His Bind resin. SDS-PAGE gel analysis revealed that the recombinant OsBIRHl protein is ~ 75 kDa in size, which is consistent with its predicted molecular mass.To elucidate the function of OsBIRHl in disease resistance response, we cloned OsBIRHl into a plant transformation binary vectoe pCAMBIA 99-1 under control of the CaMV 35S promoter and transformed Arabidopsis thalian via flora dipping. Screening and characterization of transgenic Arabidopsis plants overexpressing OsBIRHl gene are in progress.