Binding Site

Endonuclease III, iron-sulphur binding site (IPR004035)

Short name: Endouclease-III_FeS-bd_BS

Description

Endonuclease III 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 [PMID: 7773744, PMID: 9032058]. The structurally related DNA glycosylase MutY recognises and excises the mutational intermediate 8-oxoguanine-adenine mispair [PMID: 1328155]. The 3-D structures of Escherichia coli endonuclease III [PMID: 1411536] and catalytic domain of MutY [PMID: 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) [PMID: 7664751]. Two DNA-binding motifs have been proposed, one at either end of the interdomain groove: the helix-hairpin-helix (HhH) region (see IPR003265) and FCL motif, described in this entry. 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 [PMID: 7664751, PMID: 10900127].

This signature pattern covers the four Cys residues that act as 4Fe-4S ligands.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
PROSITE patterns