Nucleotide sequence of the gene for alkaline phosphatase of Thermus caldophilus GK24 and characteristics of the deduced primary structure of the enzyme.

The gene encoding Thermus caldophilus GK24 (Tca) alkaline phosphatase was cloned into Escherichia coli. The primary structure of Tca alkaline phosphatase was deduced from its nucleotide sequence. The Tca alkaline phosphatase precursor, including the signal peptide sequence, was comprised of 501 amino acid residues. Its molecular mass was determined to be 54¿ omitted¿760 Da. On the alignment of the amino acid sequence, Tca alkaline phosphatase showed sequence homology with the microbial alkaline phosphatases, 20% identity with E. coli alkaline phosphatase and 22% Bacillus subtilis (Bsu) alkaline phosphatases. High sequence identity was observed in the regions containing the Ser-102 residue of the active site, the zinc and magnesium binding sites of E. coli alkaline phosphatase. Comparison of Tca alkaline phosphatase and E. coli alkaline phosphatase structures suggests that the reduced activity of the Tca alkaline phosphatase, in the presence of zinc, is directly involved in some of the different metal binding sites. Heat-stable Tca alkaline phosphatase activity was detected in E. coli YK537, harboring pJRAP.