Two Oryza sativa Genomic DNA Clones Encoding 16.9-Kilodalton Heat-Shock Proteins.

When all living organisms are exposed to elevated temperatures, they exhibit induced synthesis of a set of proteins known as HSPs.Y Using rice heat-shock cDNA pTSS.1 (5) as a probe, we isolated two 16.9-kD HSP genes from a rice genomic library (Table I). The rice genomic library was constructed in a XgtlO vector using EcoRI-digested rice genomic DNA fragments (size between 2.0 and 4.0 kb) as inserts that were eluted from agarose gel pieces by a NA 45 DEAE membrane (Schleicher and Schuell). The heat-shock cDNA pTS1 hybridized to 2.5and 3.4-kb EcoRI-digested rice genomic DNA fragments in Southern hybridization. The DNA sequences of the two rice genomic HSP genes, Oshspl6.9A and Oshspl6.9B, were determined and analyzed as shown in Figure 1. Oshspl6.9A contained the sequence of cDNA pTS1. Comparison of Oshspl6.9A and Oshspl6.9B genes reveals that they share 98.8% homology in terms of the nucleotide sequence in the coding regions and 99.3% homology at the level of the deduced amino acid sequence. Multiple copies of the HSE-like sequence, similar to the Drosophila heat-shock consensus sequence (4), can be identified upstream from the putative TATA box, TATAAATA. The initiation site of the transcription of Oshspl6.9A and Oshspl6.9B, which was identified by the primer extension method (1), is located 131 bases upstream from the coding region and 26 bases downstream from the TATA-like region. The deduced polypeptide sequence of the Oshspl6.9A gene exhibits 73 and 84% homology to Gmhspl7.5E from soybean (2) and c5-8 from wheat (3), respectively. Table I. Characteristics of Two 16.9-kD Heat-Shock Genes from Oryza sativa