Recombinant E.coli nrdD protein

NrdD recombinant protein is derived from the nrdD gene, which encodes a class III anaerobic ribonucleotide reductase (RNR). Ribonucleotide reductases are essential enzymes responsible for the conversion of ribonucleotides to deoxyribonucleotides, a critical step in DNA synthesis and repair across all domains of life. Unlike oxygen-dependent class I and class II RNRs, class III enzymes, including NrdD, function under anaerobic conditions, making them vital for organisms inhabiting oxygen-limited environments such as certain bacteria, archaea, and pathogens.

NrdD operates through a unique radical-based mechanism involving a glycyl radical cofactor, generated by an activating enzyme (e.g., NrdG) using S-adenosylmethionine (AdoMet) and iron-sulfur clusters. This oxygen-sensitive radical enables NrdD to catalyze substrate reduction without requiring molecular oxygen, a key adaptation for anaerobic metabolism. Structurally, NrdD typically forms a homodimer with active sites coordinating essential metal ions and radical propagation pathways.

Recombinant NrdD is produced via heterologous expression in bacterial systems (e.g., *E. coli*), often with affinity tags for purification. Its study provides insights into anaerobic nucleotide metabolism, enzyme evolution, and radical-driven catalysis. Biotechnologically, NrdD has potential applications in elucidating antimicrobial drug targets, as pathogens reliant on anaerobic RNRs (e.g., *Clostridium*, *Bacteroides*) depend on NrdD for survival. Additionally, engineered NrdD variants are explored for industrial biocatalysis under oxygen-free conditions. Research continues to address challenges such as oxygen sensitivity during protein production and mechanistic nuances of radical initiation and transfer.