Bacteriophage T4 Anaerobic Ribonucleotide Reductase Contains a Stable Glycyl Radical at Position 580

摘要: Abstract It has been recently recognized that the class III anaerobic ribonucleotide reductase requires presence of a second activating gene product, NrdG. We have proposed role for NrdG involves generation an oxygen sensitive glycyl free radical within NrdD enzyme. In this article we present such T4 subunit and its dependence upon phage subunit. Initially, overexpression system was created allowed joint production With in NrdG, oxygen-sensitive cleavage observed mimicked infected Escherichia coli extracts. Under conditions with revealed strong doublet EPR signal (g = 2.0039). Isotope labeling [2H]glycine [13C]glycine, respectively, confirmed stabilized glycine radical. The unpaired electron is strongly coupled to C-2 splitting originates from one α-protons. residue at position 580 determined be containing through site-directed mutagenesis studies involving G580A mutant. specific host E. found unable activate reductase. Finally, purification holoenzyme complex contain iron, whereas polypeptide lack metal. Our results suggest tetrameric structure homodimer each single present.