Class II fumarase (fumC) and Mn-containing superoxide dismutase (sodA) genes were cloned and sequenced from Thermus thermophilus HB27. ThefumC and sodA genes existed in tandem. Comparison of the DNA and amino acid sequences of the fumC-sodA regions between T. thermophilus HB27 and Thermus aquaticus YT1 revealed that coding regions showed high homology but noncoding regions were less homologous between the two strains. The deduced amino acid sequences of T. thermophilus fumC and sodA genes showed 58.2% and 53.2% identities to those of the corresponding Escherichia coli genes, respectively. The T. thermophilus fumC gene was expressed in E. coli and the heat-resistant fumarase activity was detected at 70 degrees C.