ExplorEnz: EC 5.3.99.13

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5.3.99.13

Accepted name:

4′-phospho-dehydrooxetanocin synthase

Reaction:

dAMP + S-adenosyl-L-methionine = 4′-phospho-dehydrooxetanocin + 5′-deoxyadenosine + L-methionine (overall reaction)
(1a) S-adenosyl-L-methionine + reduced acceptor = 5′-deoxyadenosin-5′-yl radical + L-methionine + acceptor
(1b) 5′-deoxyadenosin-5′-yl radical + dAMP + acceptor = 4′-phospho-dehydrooxetanocin + 5′-deoxyadenosine + reduced acceptor

Glossary:

oxetanocin A = [(2S,3R,4R)-4-(6-amino-9H-purin-9-yl)oxetane-2,3-diyl]dimethanol

Other name(s):

oxsB (gene name)

Systematic name:

dAMP isomerase (4′-phospho-dehydrooxetanocin-forming)

Comments:

The enzyme is a B₁₂-dependent radical SAM (AdoMet) enzyme involved in the biosynthesis of oxetanocin A. The enzyme catalyses an oxidative ring contraction, forming an oxetane aldehyde. The reaction requires S-adenosyl-L-methionine, a cobalamin cofactor, and a reductant (the reductant does not show in the overall reaction because it is being restored during the cycle). The reaction is initiated by formation of 5′-deoxyadenosin-5′-yl radical, which then abstracts a hydrogen atom from C2′. The enzyme is also able to catalyse the radical mediated, stereoselective C2′-methylation of dAMP.

Links to other databases:

BRENDA, EXPASY, KEGG, MetaCyc, PDB

References:

1.	Bridwell-Rabb, J., Zhong, A., Sun, H.G., Drennan, C.L. and Liu, H.W. A B₁₂-dependent radical SAM enzyme involved in oxetanocin A biosynthesis. Nature 544 (2017) 322–326. [DOI] [PMID: 28346939]
2.	Lee, Y.H., Yeh, Y.C., Fan, P.H., Zhong, A., Ruszczycky, M.W. and Liu, H.W. Changing fates of the substrate radicals generated in the active sites of the B₁₂-dependent radical SAM enzymes OxsB and AlsB. J. Am. Chem. Soc. 145 (2023) 3656–3664. [DOI] [PMID: 36719327]

[EC 5.3.99.13 created 2024]