We report the isolation and characterization of a gene (designated mcp60) encoding the mitochondrial (mt) 60-kDa heat-shock protein (HSP60) in the fission yeast Schizosaccharomyces pombe. The deduced amino-acid sequence (582 aa) of this gene is highly similar to the known mt HSP60 from diverse organisms. When its sequence was related to the known functional domains of bacterial HSP60 (GroEL), the similarity was particularly high for the intermediate domains that connect the apical domain with the equatorial domain. The mRNA level of mcp60 increased several-fold upon temperature upshift (from 25 to 35 degrees C), while gradually decreased during sporulation. Gene disruption experiments revealed that mcp60 is essential for cell viability at all temperatures.