CATH Classification

Domain Context

CATH Clusters

Superfamily b-12 dependent (class ii) ribonucleotide reductase, Chain A, Domain 2
Functional Family

Enzyme Information

1.17.4.2
Ribonucleoside-triphosphate reductase (thioredoxin).
based on mapping to UniProt Q59490
2'-deoxyribonucleoside triphosphate + thioredoxin disulfide + H(2)O = ribonucleoside triphosphate + thioredoxin.
-!- The enzyme, characterized from the bacterium Lactobacillus leichmannii, is similar to class II ribonucleoside-diphosphate reductase (cf. EC 1.17.4.1); however, it is specific for the triphosphate versions of its substrates. -!- The enzyme contains an adenosylcobalamin cofactor that is involved in generation of a transient thiyl (sulfanyl) radical on a cysteine residue. -!- This radical attacks the substrate, forming a ribonucleotide 3'-radical, followed by water loss to form a ketyl (alpha-oxoacyl) radical. -!- The ketyl radical is reduced to 3'-keto-deoxynucleotide concomitant with formation of a disulfide anion radical between two cysteine residues. -!- A proton-coupled electron-transfer from the disulfide radical to the substrate generates a 3'-deoxynucleotide radical, and the the final product is formed when the hydrogen atom that was initially removed from the 3'-position of the nucleotide by the thiyl radical is returned to the same position. -!- The disulfide bridge is reduced by the action of thioredoxin. -!- Cf. EC 1.1.98.6.

UniProtKB Entries (1)

Q59490
RTPR_LACLE
Lactobacillus leichmannii
Adenosylcobalamin-dependent ribonucleoside-triphosphate reductase

PDB Structure

PDB 1L1L
External Links
Method X-RAY DIFFRACTION
Organism Escherichia
Primary Citation
The crystal structure of class II ribonucleotide reductase reveals how an allosterically regulated monomer mimics a dimer.
Sintchak, M.D., Arjara, G., Kellogg, B.A., Stubbe, J., Drennan, C.L.
Nat.Struct.Biol.