The bacteriophage T4 gene for the small subunit of ribonucleotide reductase contains an intron.

Abstract

The bacteriophage T4 gene nrdB codes for the small subunit of the enzyme ribonucleotide reductase. The T4 nrdB gene was localized between 136.1 kb and 137.8 kb in the T4 genetic map according to the deduced structural homology of the protein to the amino acid sequence of its bacterial counterpart, the B2 subunit of Escherichia coli. This positions the C‐terminal end of the T4 nrdB gene approximately 2 kb closer to the T4 gene 63 than earlier anticipated from genetic recombinational analyses. The most surprising feature of the T4 nrdB gene is the presence of an approximately 625 bp intron which divides the structural gene into two parts. This is the second example of a prokaryotic structural gene with an intron. The first prokaryotic intron was reported in the nearby td gene, coding for the bacteriophage T4‐specific thymidylate synthase enzyme. The nucleotide sequence at the exon‐intron junctions of the T4 nrdB gene is similar to that of the junctions of the T4 td gene: the anticipated exon‐intron boundary at the donor site ends with a TAA stop codon and there is an ATG start codon at the putative downstream intron‐exon boundary of the acceptor site. In the course of this work the denA gene of T4 (endonuclease II) was also located.

Identification and isolation of the gene encoding the small subunit of ribonucleotide reductase from Saccharomyces cerevisiae: DNA damage-inducible gene required for mitotic viability.

“…It contains stoichiometric amounts of a nonheme iron center and a tyrosyl free radical which are essential for activity (38). These characteristics are typical of other eucaryotic and viral ribonucleotide reductases and are similar to those of the enzymes from Escherichia coli and phage T4 (30,39).…”

Ribonucleotide Reductases

“…Both are highly homologous to the host enzymes. The phage genes possess an important distinguishing feature: nrdB (131) and nrdD (14) contain introns.…”

Molecular cloning and expression of the functional gene encoding the M2 subunit of mouse ribonucleotide reductase: a new dominant marker gene.

“…It was recently demonstrated that the gene encoding the small subunit of the bacteriophage T4 ribonucleotide reductase (nrdB) contains an intron (Gott et al, 1986;Sjoberg et al, 1986). There is a high degree of similarity between this intron and eukaryotic introns, suggesting a common ancestry.…”