Cloning and characterization of hsc1⁺, a heat shock cognate gene of the fission yeast Schizosaccharomyces pombe

A heat shock cognate gene from the fission yeast Schizosaccharomyces pombe (Sp), designated hsc1⁺, was cloned. The putative translation product of hsc1⁺ contains 613 aa, with an estimated molecular mass of 67,205 Da, and is more similar to the Saccharomyces cerevisiae (Sc) heat shock cognate protein SSB1 (69% identity) than the Sp heat-inducible ssp1⁺ gene product (41% identity). The hsc1⁺ mRNA was abundant during steady-state growth at 23°C and decreased upon heat shock. Immunoblot analysis showed that the hsc1 protein is also abundant and constitutively expressed, however, we could not observe significant change in the protein level upon heat shock. DNA blot analyses indicated that hsc1⁺ is localized in Sp chromosome II, and suggested that the Sp genome contains a relatively smaller number of HSP70 genes compared with the Sc genome.