A new class EC 7, Translocases, has been added to the EC list. It will be part of ENZYME from release 2018_10. Read more about EC 7 here.

ENZYME entry: EC 2.5.1.17

Accepted Name
Corrinoid adenosyltransferase.
Alternative Name(s)
Aquacob(I)alamin adenosyltransferase.
Aquocob(I)alamin vitamin B12s adenosyltransferase.
ATP:cob(I)alamin Co-beta-adenosyltransferase.
ATP:corrinoid adenosyltransferase.
Cob(I)alamin adenosyltransferase.
Cob(I)yrinic acid a,c-diamide adenosyltransferase.
Reaction catalysed
  • 2 ATP + 2 cob(II)alamin + a reduced flavoprotein <=> 2 triphosphate + 2 adenosylcob(III)alamin + an oxidized flavoprotein
  • 2 ATP + 2 cob(II)yrinic acid a,c-diamide + a reduced flavoprotein <=> 2 triphosphate + 2 adenosylcob(III)yrinic acid a,c-diamide + an oxidized flavoprotein
Comment(s)
  • The corrinoid adenosylation pathway comprises three steps: (i) reduction of Co(III) to Co(II) by a one-electron transfer.
  • This can occur non-enzymically in the presence of dihydroflavin nucleotides or reduced flavoproteins.
  • (ii) Co(II) is bound by corrinoid adenosyltransferase, resulting in displacement of the lower axial ligand by an aromatic residue.
  • The reduction potential of the 4-coordinate Co(II) intermediate is raised by ~250 mV compared with the free compound, bringing it to within physiological range.
  • This is followed by a second single-electron transfer from either free dihydroflavins or the reduced flavin cofactor of flavoproteins, resulting in reduction to Co(I).
  • (iii) the Co(I) conducts a nucleophilic attack on the adenosyl moiety of ATP, resulting in transfer of the deoxyadenosyl group and oxidation of the cobalt atom to Co(III) state.
  • Three types of corrinoid adenosyltransferases, not related by sequence, have been described.
  • In the anaerobic bacterium Salmonella enterica they are encoded by the cobA gene (a housekeeping enzyme involved in both adenosylcobalamin de novo biosynthesis and salvage), the pduO gene (involved in (S)-propane-1,2-diol utilization), and the eutT gene (involved in ethanolamine utilization).
  • Since EutT hydrolyzes triphosphate during catalysis, it is classified as a separate enzyme.
  • The mammalian enzyme belongs to the PduO type.
  • The enzyme can act on other corrinoids, such as cob(II)inamide.
Cross-references
BRENDA2.5.1.17
EC2PDB2.5.1.17
ExplorEnz2.5.1.17
PRIAM enzyme-specific profiles2.5.1.17
KEGG Ligand Database for Enzyme Nomenclature2.5.1.17
IUBMB Enzyme Nomenclature2.5.1.17
IntEnz2.5.1.17
MEDLINEFind literature relating to 2.5.1.17
MetaCyc2.5.1.17
UniProtKB/Swiss-Prot
P0A9H6, BTUR_ECOL6;  P0A9H5, BTUR_ECOLI;  P31570, BTUR_SALTY;  
Q9I472, COBO_PSEAE;  P29930, COBO_PSEDE;  P65644, EUTT_ECOL6;  
P65643, EUTT_ECOLI;  Q9ZFV4, EUTT_SALTY;  Q58D49, MMAB_BOVIN;  
Q96EY8, MMAB_HUMAN;  Q9D273, MMAB_MOUSE;  O34899, PDUO_BACSU;  
P45515, PDUO_CITFR;  P64804, PDUO_MYCBO;  P53523, PDUO_MYCLE;  
P9WP98, PDUO_MYCTO;  P9WP99, PDUO_MYCTU;  

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