EC Explorer

4.1.99.15

S-specific spore photoproduct lyase

(5S)-5,6-dihydro-5-(thymidin-7-yl)thymidine (in DNA) + S-adenosyl-L-methionine = thymidylyl-(3′→5′)-thymidylate (in DNA) + 5′-deoxyadenosine + L-methionine

SAM, SP lyase, SPL, SplB, SplG

S-specific spore photoproduct pyrimidine-lyase

37290-70-3

An iron-sulfur protein (contains one [4Fe-4S]²⁺ per enzyme monomer). The 5′-deoxy-adenosine radical formed after electron transfer from the [4Fe-4S] cluster to the S-adenosyl-L-methionine, initiates the repair by abstracting the C-6 hydrogen of the spore photoproduct lesion. The C-C bond linking the two pyrimidines undergoes fragmentation to give an allyl-type radical. The thermodynamically problematic last step is the transfer of the hydrogen atom back from the 5′-deoxyadenosine to the thymine monomer radical, which completes the repair process [3]. The enzyme from Bacillus subtilis is specific for the (5S)-configured spore photoproduct [4]. For the enzyme from Clostridium acetobutylicum a (5R)-specificity was demonstrated with spore photoproduct in double-helical DNA (cf. EC 4.1.99.14 [R-specific spore photoproduct lyase]).

created 2009, deleted 2010