title: Interaction of apurinic/apyrimidinic endonuclease 2 (Apn2) with Myh1 DNA glycosylase in fission yeast.
abstract: Oxidative DNA damage is repaired primarily by the base excision repair (BER) pathway in a process initiated by removal of base lesions or mismatched bases by DNA glycosylases. MutY homolog (MYH, MUTYH, or Myh1) is a DNA glycosylase which excises adenine paired with the oxidative lesion 8-oxo-7,8-dihydroguanine (8-oxoG, or G°), thus reducing G:C to T:A mutations. The resulting apurinic/apyrimidinic (AP) site is processed by an AP-endonuclease or a bifunctional glycosylase/lyase. We show here that the major Schizosaccharomyces pombe AP endonuclease, Apn2, binds to the inter-domain connector located between the N- and C-terminal domains of Myh1. This Myh1 inter-domain connector also interacts with the Hus1 subunit of the Rad9-Rad1-Hus1 checkpoint clamp. Mutagenesis studies indicate that Apn2 and Hus1 bind overlapping but different sequence motifs on Myh1. Mutation on I(261) of Myh1 reduces its interaction with Hus1, but only slightly attenuates its interaction with Apn2. However, E(262) of Myh1 is a key determinant for both Apn2 and Hus1 interactions. Like human APE1, Apn2 has 3'-phosphodiesterase activity. However, unlike hAPE1, Apn2 has a weak AP endonuclease activity which cleaves the AP sites generated by Myh1 glycosylase. Functionally, Apn2 stimulates Myh1 glycosylase activity and Apn2 phosphodiesterase activity is stimulated by Myh1. The cross stimulation of Myh1 and Apn2 enzymatic activities is dependent on their physical interaction. Thus, Myh1 and Apn2 constitute an initial BER complex.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
authors.forename: Jin
authors.initials: J
authors.lastname: Jin
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
authors.forename: Bor-Jang
authors.initials: BJ
authors.lastname: Hwang
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
authors.forename: Po-Wen
authors.initials: PW
authors.lastname: Chang
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA; Center for Biomolecular Therapeutics, University of Maryland School of Medicine, Rockville, MD 20850, USA.
authors.forename: Eric A
authors.initials: EA
authors.lastname: Toth
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA. Electronic address: aluchang@umaryland.edu.
authors.forename: A-Lien
authors.initials: AL
authors.lastname: Lu
mesh_terms: D001080:Apurinic Acid / Q000737:chemistry; D003001:Cloning, Molecular; D053837:DNA Cleavage; D045647:DNA Glycosylases / Q000737:chemistry*; D004260:DNA Repair; D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase / Q000737:chemistry*; D004926:Escherichia coli; D016681:Genome, Fungal; D042822:Genomic Instability; D007700:Kinetics; D012568:Schizosaccharomyces / Q000201:enzymology* / Q000235:genetics; D029702:Schizosaccharomyces pombe Proteins / Q000737:chemistry*
chemical_list: D004271:DNA, Fungal; D029702:Schizosaccharomyces pombe Proteins; D001080:Apurinic Acid; D045647:DNA Glycosylases; C061738:mutY adenine glycosylase; C480729:Apn2 protein, S pombe; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase
keywords: AP endonuclease; DNA glycosylase; DNA repair; Phosphodiesterase; Schizosaccharomyces pombe; Yeast