Sequencing and enhanced expression of the gene encoding diadenosine 5',5'''-P1, P4-tetraphosphate (Ap4A) phosphorylase in Saccharomyces cerevisiae.

The gene, DTP, coding for diadenosine 5',5'''-P1, P4-tetraphosphate (Ap4A) phosphorylase was isolated from a Saccharomyces cerevisiae genomic DNA library in lambda gt11. In yeast and Escherichia coli transformed with the multicopy vector, YEp352, containing the cloned DTP gene, the Ap4A phosphorylase was produced at levels nine- to 17-fold higher than in untransformed hosts. The nucleotide (nt) sequence was determined. The gene codes for a polypeptide chain of 321 amino acids (aa). Two-aa sequence motifs of possible significance were identified: a potential adenine nt binding site and a potential phosphorylation site. The DTP gene is located on yeast chromosome III and is present as a single copy. Although multicopy vector expression increased the Ap4A phosphorylase activity ninefold above the endogenous activity in transformed yeast, the intracellular concentration of Ap4A did not decrease and the growth rate of the yeast was unchanged.