CLONING AND SEQUENCE-ANALYSIS OF THE GENE FOR PHOSPHOENOLPYRUVATE CARBOXYLASE FROM AN EXTREME THERMOPHILE, THERMUS SP

The ppc gene, which encodes phosphoenolpyruvate carboxylase (PEPC) of an extreme thermophile, Thermus sp,, was cloned and sequenced. The ppc gene had a high G + C content (69.2%). An open reading frame for a 85 7-amino-acid polypeptide was found in the gene. The calculated molecul ar mass was 95,632, The amino acid sequence of Thermus PEPC was 31-37% identical and 52-57% similar to those of 17 PEPCs from mesophilic org anisms, No Cys residue was found in the polypeptide, demonstrating tha t this residue is not essential for the catalytic activity of PEPC. Th e cloned gene was expressed in Escherichia coli. and thermostable PEPC was obtained.