High impact information on ENDOG

• Endo G is synthesized as a propeptide with an amino-terminal presequence that targets the nuclease to mitochondria [1].
• Primers for mitochondrial DNA replication generated by endonuclease G [1].
• Recognition of (dG)n.(dC)n sequences by endonuclease G. Characterization of the calf thymus nuclease [2].
• Endo G is highly specific for (dG)n.(dC)n tracts in DNA, nicking either strand of relaxed substrates with similar kinetics [2].
• Endo G efficiently cleaves (dC)n but not (dG)n runs in single-stranded DNA, suggesting that it may recognize an asymmetric strand conformation of the homopolymer tracts [2].

Biological context of ENDOG

• In the present study, we find that Endonuclease G partially purified from calf thymus nuclei will extensively degrade both viral ss- and dsDNAs in vitro, and that the enzyme possesses biochemical properties and specificity for nucleotide sequences in DNA that are strongly related or identical to those of the mt endonuclease [3].
• These nucleolytic properties of Endo G in vitro suggest its possible involvement in the maintenance of mtDNA by eliminating defective genomes from the multicopy pool [4].
• Cisplatin-mediated DNA damage, which causes intrastrand crosslinks between adjacent guanine residues, also facilitated Endo G digestion, indicating that the enzyme can recognize local distortions in the duplex DNA introduced by adducts [4].

Anatomical context of ENDOG

• The nuclear Endonuclease G first identified from its selective targeting of several (dG)n:(dC)n tracts in vitro (where N = 3-29), was subsequently purified from calf thymus nuclei and shown to be a homodimer of a approximately 26-kDa polypeptide [Côté, J. et al. (1989) J. Biol. Chem., 264, 3301-3310] [3].
• The 55-kDa enzyme and Endo G were extracted from bovine heart mitochondria with 0.4 M NaCl [5].
• A novel endonuclease of 55-kDa was found in rat liver mitochondria by a zymographic assay, in addition to the 29 kDa enzyme that is well-known as endonuclease G (Endo G) [5].

Associations of ENDOG with chemical compounds

• Treatment of DNA with L-ascorbic acid or peplomycin, that introduces single-strand breaks through active oxygen radicals, greatly enhanced the susceptibility to nucleolytic attacks from Endo G [4].
• Action of mitochondrial endonuclease G on DNA damaged by L-ascorbic acid, peplomycin, and cis-diamminedichloroplatinum (II) [4].
• Phosphatidylcholine and phosphatidylethanolamine, the major constituents of the mitochondrial inner membrane, stimulated purified Endo G activity 5- to 10-fold [6].

Analytical, diagnostic and therapeutic context of ENDOG

• During purification the 55-kDa enzyme and Endo G were copurified because of their similar chromatographic behavior, so they were separated by gel filtration or electrophoresis in the presence of SDS and the proteins were then renatured [5].

References