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QuickView for Endonuclease III-like, conserved site-2 (biogroup)
- 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. The structurally related DNA glycosylase MutYrecognises and excises the mutational intermediate 8-oxoguanine-adenine mispair. The 3-D structures of Escherichia coli endonuclease III and catalytic domain of MutY have been determined. Thestructures 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 theFe4S4 cluster. The cluster is bound entirely within the C-terminal loop by four cysteine residues with a ligation patternCys-(Xaa)6-Cys-(Xaa)2-Cys-(Xaa)5-Cys which is distinct from all other known Fe4S4 proteins. This structural motif isreferred to as a Fe4S4 cluster loop (FCL). Two DNA-binding motifs have been proposed, one at either end of theinterdomain groove: the helix-hairpin-helix (HhH) and FCL motifs . The primary role of the iron-sulphur cluster appears toinvolve positioning conserved basic residues for interaction with the DNA phosphate backbone by forming the loop ofthe FCL motif.
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