Escherichia coli endonuclease III (EC 4.2.99.18) [1] is a DNA repair enzyme that acts both as a DNA N-glycosylase, removing oxidised pyrimidines from DNA, and as an apurinic/apyrimidinic (AP) endonuclease, introducing a single-strand nick at the site ...
Escherichia coli endonuclease III (EC 4.2.99.18) [1] is a DNA repair enzyme that acts both as a DNA N-glycosylase, removing oxidised pyrimidines from DNA, and as an apurinic/apyrimidinic (AP) endonuclease, introducing a single-strand nick at the site from which the damaged base was removed. Endonuclease III is an iron-sulfur protein that binds a single 4Fe-4S cluster. The 4Fe-4S cluster does not seem to be important for catalytic activity, but is probably involved in the proper positioning of the enzyme along the DNA strand [2]. The 4Fe-4S cluster is bound by four cysteines which are all located in a 17 amino acid region at the C-terminal end of endonuclease III. A similar region is also present in the central section of mutY and in the C-terminus of ORF-10 and of the Micro-coccus UV endonuclease [4].
HhH-GPD superfamily base excision DNA repair protein
This family contains a diverse range of structurally related DNA repair proteins. The superfamily is called the HhH-GPD family after its hallmark Helix-hairpin-helix and Gly/Pro rich loop followed by a conserved aspartate [2]. This includes endonucle ...
This family contains a diverse range of structurally related DNA repair proteins. The superfamily is called the HhH-GPD family after its hallmark Helix-hairpin-helix and Gly/Pro rich loop followed by a conserved aspartate [2]. This includes endonuclease III, EC:4.2.99.18 and MutY an A/G-specific adenine glycosylase, both have a C terminal 4Fe-4S cluster. The family also includes 8-oxoguanine DNA glycosylases such as Swiss:P53397. The methyl-CPG binding protein MBD4 Swiss:Q9Z2D7 also contains a related domain [1] that is a thymine DNA glycosylase. The family also includes DNA-3-methyladenine glycosylase II EC:3.2.2.21 and other members of the AlkA family.