Enhanced activity of adenine-DNA glycosylase (Myh) by apurinic/apyrimidinic endonuclease (Ape1) in mammalian base excision repair of an A/GO mismatch

• Published in: Nucleic acids research Vol. 29; no. 3; pp. 743 - 752
• Main Authors: Yang, H, Clendenin, W M, Wong, D, Demple, B, Slupska, M M, Chiang, J H, Miller, J H
• Format: Journal Article
• Language: English
• Published: England Oxford Publishing Limited (England) 01-02-2001; Oxford University Press
• Subjects: Amino Acid Sequence; Animals; Apurinic Acid - metabolism; Base Pair Mismatch - genetics; Carbon-Oxygen Lyases - metabolism; Cloning, Molecular; Deoxyribonuclease IV (Phage T4-Induced); DNA - genetics; DNA - metabolism; DNA Damage; DNA Glycosylases; DNA Repair; DNA, Complementary - chemistry; DNA, Complementary - genetics; DNA, Complementary - isolation & purification; DNA-(Apurinic or Apyrimidinic Site) Lyase; Electrophoresis, Polyacrylamide Gel; Escherichia coli Proteins; Guanine - analogs & derivatives; Guanine - metabolism; Mice; Molecular Sequence Data; N-Glycosyl Hydrolases - genetics; N-Glycosyl Hydrolases - metabolism; Protein Binding; Sequence Alignment; Sequence Analysis, DNA; Sequence Homology, Amino Acid; Substrate Specificity
• ISSN: 1362-4962; 0305-1048; 1362-4962
• DOI: 10.1093/nar/29.3.743

Adenine-DNA glycosylase MutY of Escherichia coli catalyzes the cleavage of adenine when mismatched with 7,8-dihydro-8-oxoguanine (GO), an oxidatively damaged base. The biological outcome is the prevention of C/G-->A/T transversions. The molecular mechanism of base excision repair (BER) of A/GO in mammals is not well understood. In this study we report stimulation of mammalian adenine-DNA glycosylase activity by apurinic/apyrimidinic (AP) endonuclease using murine homolog of MutY (Myh) and human AP endonuclease (Ape1), which shares 94% amino acid identity with its murine homolog Apex. After removal of adenine by the Myh glycosylase activity, intact AP DNA remains due to lack of an efficient Myh AP lyase activity. The study of wild-type Ape1 and its catalytic mutant H309N demonstrates that Ape1 catalytic activity is required for formation of cleaved AP DNA. It also appears that Ape1 stimulates Myh glycosylase activity by increasing formation of the Myh-DNA complex. This stimulation is independent of the catalytic activity of Ape1. Consequently, Ape1 preserves the Myh preference for A/GO over A/G and improves overall glycosylase efficiency. Our study suggests that protein-protein interactions may occur in vivo to achieve efficient BER of A/GO.