Abstract
The nucleotide sequence of the Escherichia coli K-12 DNA comprising the operon for the structural genes of the subunits of ribonucleotide diphosphate reductase has been determined. The DNA sequenced maps at 48.5 minutes on the E. coli chromosome and includes a total length of 8557 nucleotides. An open reading frame between nucleotides 3506 and 5834, encoding a 776-amino acid polypeptide chain with a molecular weight of 87,532, has been identified as the nrdA gene. An open reading frame between nucleotides 6012 and 7139, encoding a 375-amino acid polypeptide with a molecular weight of 43,466, has been identified as the nrdB gene. The sequences reveal not only the primary structures for both subunits, but also some interesting aspects of potential regulatory sites.