Bacteriophage T4 gene 55.9 encodes an activity required for anaerobic ribonucleotide reduction.

摘要: Bacteriophage T4 contains a phage-encoded anaerobic ribonucleoside triphosphate reductase, nrdD, previously named sunY. An open reading frame, 55.9, that resides downstream of the phage reductase was observed to have amino acid sequence similarity with E. coli pyruvate formate-lyase (Pfl) activating enzyme. A stop codon engineered into cloned 55.9 gene and then recombined back genome. Phage-infected extracts lack functional product 6-fold reduction in ribonucleotide activity are unable activate overexpressed NrdD. Restoration possible when 55.9- nrdD- T4-infected Escherichia were conjointly assayed. Comparing burst size infections parental indicates de novo synthesis deoxyribonucleotides is nearly abolished lacking product. We propose encodes an enzyme activates NrdD by generating glycyl radical reductase. The homology between Pfl (in this communication renamed NrdG) function as well presumably remnant ancient heritage reductases.