EC - Ribonucleoside-triphosphate reductase (formate)

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IntEnz Enzyme Nomenclature


Accepted name:
ribonucleoside-triphosphate reductase (formate)
Other names:
nrdD (gene name)
class III ribonucleoside-triphosphate reductase
anaerobic ribonucleotide reductase
anaerobic ribonucleoside-triphosphate reductase
Systematic name:
ribonucleoside-5'-triphosphate:formate 2'-oxidoreductase



The enzyme, which is expressed in the bacterium Escherichia coli during anaerobic growth, contains an iron sulfur center. The active form of the enzyme contains an oxygen-sensitive glycyl (1-amino-2-oxoethan-1-yl) radical that is generated by the activating enzyme NrdG via chemistry involving S-adenosylmethionine (SAM) and a [4Fe-4S] cluster. The glycyl radical is involved in generation of a transient thiyl (sulfanyl) radical on a cysteine residue, which attacks the substrate, forming a ribonucleotide 3'-radical, followed by water loss to form a ketyl (α-oxoalkyl) radical. The ketyl radical gains an electron from a cysteine residue and a proton from formic acid, forming 3'-keto-deoxyribonucleotide and generating a thiosulfuranyl (1λ4-disulfan-1-yl) radical bridge between methionine and cysteine residues. Oxidation of formate by the thiosulfuranyl radical results in the release of CO2 and regeneration of the thiyl radical. cf. EC, ribonucleoside-diphosphate reductase and EC, ribonucleoside-triphosphate reductase (thioredoxin).

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Structural data: CSA , EC2PDB


  1. Eliasson, R., Pontis, E., Fontecave, M., Gerez, C., Harder, J., Jörnvall, H., Krook, M., Reichard, P.
    Characterization of components of the anaerobic ribonucleotide reductase system from Escherichia coli.
    J. Biol. Chem. 267 : 25541-25547 (1992). [PMID: 1460049]
  2. Mulliez, E., Fontecave, M., Gaillard, J., Reichard, P.
    An iron-sulfur center and a free radical in the active anaerobic ribonucleotide reductase of Escherichia coli.
    J. Biol. Chem. 268 : 2296-2299 (1993). [PMID: 8381402]
  3. Mulliez, E., Ollagnier, S., Fontecave, M., Eliasson, R., Reichard, P.
    Formate is the hydrogen donor for the anaerobic ribonucleotide reductase from Escherichia coli.
    Proc. Natl. Acad. Sci. U.S.A. 92 : 8759-8762 (1995). [PMID: 7568012]
  4. Ollagnier, S., Mulliez, E., Schmidt, P. P., Eliasson, R., Gaillard, J., Deronzier, C., Bergman, T., Gräslund, A., Reichard, P., Fontecave, M.
    Activation of the anaerobic ribonucleotide reductase from Escherichia coli. The essential role of the iron-sulfur center for S-adenosylmethionine reduction.
    J. Biol. Chem. 272 : 24216-24223 (1997). [PMID: 9305874]
  5. Wei, Y., Mathies, G., Yokoyama, K., Chen, J., Griffin, R. G., Stubbe, J.
    A chemically competent thiosulfuranyl radical on the Escherichia coli class III ribonucleotide reductase.
    J. Am. Chem. Soc. 136 : 9001-9013 (2014). [PMID: 24827372]

[EC created 2017]