Reaction Scheme: biotin synthase, radical SAM superfamily Reaction 44

Scheme name: biotin synthase, radical SAM superfamily
Reaction: biotin synthase
Description:The enzyme binds a [4Fe-4S] and a [2Fe-2S] cluster. In every reaction cycle, the enzyme consumes two molecules of AdoMet, each producing 5'-deoxyadenosine and a putative dethiobiotinyl carbon radical. Reaction with another equivalent of AdoMet results in abstraction of the C6 methylene pro-S hydrogen atom from 9-mercaptodethiobiotin, and the resulting carbon radical is quenched via formation of an intramolecular C-S bond, thus closing the biotin thiophane ring. The sulfur donor is believed to be the [2Fe-2S] cluster, which is sacrificed in the process, so that in vitro the reaction is a single turnover. In vivo, the [2Fe-2S] cluster can be reassembled by the Isc or Suf iron-sulfur cluster assembly systems, to allow further catalysis.
Curator notes:

Database References

DB Name DB Identifier Evidence Code Evidence Code Reference
SFLD EFD 1926420 IDA 8729 8730 8731

Reaction

biotin synthase

+ 2 + + 2 + 2 + 2 + + 2
thiol group
29917		 S-adenosyl-L-methionine zwitterion
59789		 dethiobiotin(1-)
57861		 di-mu-sulfido-diiron(1+)
33738		 H group
64428		 5'-deoxyadenosine
17319		 L-methionine zwitterion
57844		 biotinate
57586		 di-mu-sulfido-diiron(2+)
33737

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