|SMART accession number:||SM00525|
|Description:||iron-sulpphur binding domain in DNA-(apurinic or apyrimidinic site) lyase (subfamily of ENDO3)|
|Interpro abstract (IPR003651):|
Endonuclease III (EC 126.96.36.199) is a DNA repair enzyme which removes a number of damaged pyrimidines from DNA via its glycosylase activity and also cleaves the phosphodiester backbone at apurinic / apyrimidinic sites via a beta-elimination mechanism [(PUBMED:7773744), (PUBMED:9032058)]. The structurally related DNA glycosylase MutY recognises and excises the mutational intermediate 8-oxoguanine-adenine mispair [(PUBMED:1328155)]. The 3-D structures of Escherichia coli endonuclease III [(PUBMED:1411536)] and catalytic domain of MutY [(PUBMED:9846876)] have been determined. The structures contain two all-alpha domains: a sequence-continuous, six-helix domain (residues 22-132) and a Greek-key, four-helix domain formed by one N-terminal and three C-terminal helices (residues 1-21 and 133-211) together with the Fe4S4 cluster. The cluster is bound entirely within the C-terminal loop by four cysteine residues with a ligation pattern Cys-(Xaa)6-Cys-(Xaa)2-Cys-(Xaa)5-Cys which is distinct from all other known Fe4S4 proteins. This structural motif is referred to as a Fe4S4 cluster loop (FCL) [(PUBMED:7664751)]. Two DNA-binding motifs have been proposed, one at either end of the interdomain groove: the helix-hairpin-helix (HhH) and FCL motifs. The primary role of the iron-sulphur cluster appears to involve positioning conserved basic residues for interaction with the DNA phosphate backbone by forming the loop of the FCL motif [(PUBMED:7664751), (PUBMED:10900127)].
The iron-sulphur cluster loop (FCL) is also found in DNA-(apurinic or apyrimidinic site) lyase, a subfamily of endonuclease III. The enzyme has both apurinic and apyrimidinic endonuclease activity and a DNA N-glycosylase activity. It cuts damaged DNA at cytosines, thymines and guanines, and acts on the damaged strand 5' of the damaged site. The enzyme binds a 4Fe-4S cluster which is not important for the catalytic activity, but is probably involved in the alignment of the enzyme along the DNA strand.
|GO function:||4 iron, 4 sulfur cluster binding (GO:0051539)|
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