Glutamine nucleotide sequence of Saccharomyces cerevisiae ADE4 encoding phosphoribosylpyrophosphate amidotransferase.

Saccharomyces cerevisiae gene ADE4 encoding glutamine phosphoribosylpyrophosphate amidotransferase (amidophosphoribosyltransferase) has been cloned by complementation of an ade4 auxotroph. The nucleotide sequence of ADE4 along with upstream and downstream flanking sequences was determined. The ADE4 structural gene consists of 1530 base pairs from which a 510-amino acid translation product, Mr = 56,691, was deduced. Yeast amidophosphoribosyltransferase is homologous to the enzymes from Escherichia coli and Bacillus subtilis. The active site cysteine residue in the bacterial amidophosphoribosyltransferases which functions in glutamine amide transfer is conserved in the yeast enzyme. Yeast amidophosphoribosyltransferase does not contain the previously deduced sequence required for binding of a [4Fe-4S] center indicating that a [4Fe-4S] center is an unlikely component of the yeast enzyme. Amidophosphoribosyltransferase was stable in growing and nongrowing cells and was not inactivated or degraded. Thus in the group, S. cerevisiae, E. coli, B. subtilis, the content of a [4Fe-4S] cluster in amidophosphoribosyltransferase correlates with a mechanism for oxygen-dependent inactivation of the enzyme. Northern blots demonstrate that ADE4 expression is transcriptionally regulated. The 5' end of the ADE4 mRNA was identified by nuclease S1 mapping.