Human phosphoribosylformylglycineamide amidotransferase (FGARAT): regionalmapping, complete coding sequence, isolation of a functional genomic clone, and DNA sequence analysis

Purines play essential roles in many cellular functions, including DNA repl ication, transcription, intra- and extra-cellular signaling, energy metabol ism, and as coenzymes for many biochemical reactions. The de-novo synthesis of purines requires 10 enzymatic steps for the production of inosine monop hosphate (IMP). Defects in purine metabolism are associated with human dise ases. Further, many anticancer agents function as inhibitors of the de-novo biosynthetic pathway. Genes or cDNAs for most of the enzymes comprising th is pathway have been isolated from humans or other mammals. One notable exc eption is the phosphoribosylformylglycineamide amidotransferase (FGARAT) ge ne, which encodes the fourth step of this pathway. This gene has been clone d from numerous microorganisms and from Drosophila melanogaster and C. eleg ans. We report here the identification of a human cDNA containing the codin g region of the FGARAT mRNA and the isolation of a Fl clone that contains a n intact human FGARAT gene. The P1 clone corrects the purine auxotrophy and protein deficiency of Chinese hamster ovary (CHO) cell mutants (AdeB) defi cient in both the activity and the: protein for FGARAT. The pi clone was us ed to regionally map the FGARAT gene to chromosome region 17p13, a location consistent with our prior assignment of this gene to chromosome 17. A comp arison of the DNA sequence of the human FGARAT and FGARAT DNA sequence from 17 other organisms is reported. The isolation of this gene means that DNA clones for all the 10 steps of IMP synthesis have been isolated from humans or other mammals. (C) 1999 Elsevier Science B.V. All rights reserved.