CLONING AND CHARACTERIZATION OF A CDNA-ENCODING AN 18.0-KDA CLASS-I LOW-MOLECULAR-WEIGHT HEAT-SHOCK PROTEIN FROM RICE

A novel cDNA clone, Oshsp18.0 cDNA, encoding a rice (Oryza sativa L. c v. Tainong 67) 18.0-kDa heat-shock protein (HSP), was isolated from a cDNA library of heat-shocked rice seedlings by use of the rice HSP cDN A, Oshsp17.3 cDNA, as a probe. The sequence showed that Oshsp18.0 cDNA contains a 749-bp insert encoding an ORF of 160 amino acids, with a p redicted molecular mass of 18.0 kDa and a pi of 7.3. Sequence comparis on reveals that Oshsp18.0 cDNA is highly homologous to other low-molec ular-weight (LMW) HSP cDNAs. Also, the results of hybrid-selected in v itro translation clearly establish that Oshsp18.0 cDNA is the rice 18. 0-kDa LMW HSP-encoding cDNA clone. The recombinant Oshsp18.0 fusion pr otein produced in Escherichia coli was of the size predicted, and was recognized by the class-I rice 16.9-kDa HSP antiserum. The results sug gest that Oshsp18.0 cDNA is an 18.0-kDa class-I LMW HSP- encoding cDNA clone from rice.