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 c loned into Escherichia coli. The primary structure of Tca alkaline phosphat ase was deduced from its nucleotide sequence. The Tca alkaline phosphatase precursor, including the signal peptide sequence, was comprised of 501 amin o acid residues. Its molecular mass was determined to be 54760 Da. On the a lignment of the amino acid sequence, Tca alkaline phosphatase showed sequen ce homology with the microbial alkaline phosphatases, 20% identity with E. coli alkaline phosphatase and 22% Bacillus subtilis (Bsu) alkaline phosphat ases. 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. c oli alkaline phosphatase structures suggests that the reduced activity of t he Tca alkaline phosphatase, in the presence of zinc, is directly involved in some of the different metal binding sites. Heat-stable Tca alkaline phos phatase activity was detected in E. coli YK537, harboring pJRAP. (C) 1999 F ederation of European Microbiological Societies. Published by Elsevier Scie nce B.V. All rights reserved.