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- * Endonuclease III iron-sulfur binding region signature *
- *********************************************************
-
- Escherichia coli endonuclease III (EC 3.1.25.2) (gene nth) [1] is a DNA repair
- enzyme that acts both as a DNA N-glycosylase, removing oxidized 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].
-
- Endonuclease III is evolutionary related to the following proteins:
-
- - Escherichia coli DNA repair protein mutY, which is an adenine glycosylase.
- MutY is a larger protein (350 amino acids) than endonuclease III (211 amino
- acids).
- - ORF10 in plasmid pFV1 of the thermophilic archaebacteria Methanobacterium
- thermoformicicum [3]. Restriction methylase m.MthTI, which is encoded by
- this plasmid, generates 5-methylcytosine which is subject to deamination
- resulting in G-T mismatches. This protein could correct these mismatches.
-
- 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 ORF10.
-
- -Consensus pattern: C-x(3)-K-P-[KR]-C-x(2)-C-x(5)-C
- [The four C's are 4Fe-4S ligands]
- -Sequences known to belong to this class detected by the pattern: ALL.
- -Other sequence(s) detected in SWISS-PROT: NONE.
- -Last update: October 1993 / Text revised.
-
- [ 1] Kuo C.-F., McRee D., Fisher C.L., O'Handley S.F., Cunnigham R.P.,
- Tainer J.A.
- Science 258:434-440(1992).
- [ 2] Thomson A.J.
- Curr. Biol. 3:173-174(1993).
- [ 3] Noelling J., van Eeden F.J.M., Eggen R.I.L., de Vos W.M.
- Nucleic Acids Res. 20:6501-6507(1992).
-