title: Role of the unstructured N-terminal domain of the hAPE1 (human apurinic/apyrimidinic endonuclease 1) in the modulation of its interaction with nucleic acids and NPM1 (nucleophosmin).
abstract: The hAPE1 (human apurinic/apyrimidinic endonuclease 1) is an essential enzyme, being the main abasic endonuclease in higher eukaryotes. However, there is strong evidence to show that hAPE1 can directly bind specific gene promoters, thus modulating their transcriptional activity, even in the absence of specific DNA damage. Recent findings, moreover, suggest a role for hAPE1 in RNA processing, which is modulated by the interaction with NPM1 (nucleophosmin). Independent domains account for many activities of hAPE1; however, whereas the endonuclease and the redox-active portions of the protein are well characterized, a better understanding of the role of the unstructured N-terminal region is needed. In the present study, we characterized the requirements for the interaction of hAPE1 with NPM1 and undamaged nucleic acids. We show that DNA/RNA secondary structure has an impact on hAPE1 binding in the absence of damage. Biochemical studies, using the isolated N-terminal region of the protein, reveal that the hAPE1 N-terminal domain represents an evolutionary gain of function, since its composition affects the protein's stability and ability to interact with both nucleic acids and NPM1. Although required, however, this region is not sufficient itself to stably interact with DNA or NPM1.
authors.affiliation: Department of Medical and Biological Sciences, University of Udine, 33100 Udine, Italy.
authors.forename: Mattia
authors.initials: M
authors.lastname: Poletto
authors.forename: Carlo
authors.initials: C
authors.lastname: Vascotto
authors.forename: Pasqualina L
authors.initials: PL
authors.lastname: Scognamiglio
authors.forename: Lisa
authors.initials: L
authors.lastname: Lirussi
authors.forename: Daniela
authors.initials: D
authors.lastname: Marasco
authors.forename: Gianluca
authors.initials: G
authors.lastname: Tell
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004249:DNA Damage; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase / Q000737:chemistry* / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry* / Q000235:genetics; D009696:Nucleic Acids / Q000737:chemistry* / Q000235:genetics; D000090243:Nucleophosmin; D011485:Protein Binding / Q000235:genetics; D012313:RNA / Q000235:genetics / Q000378:metabolism; D017385:Sequence Homology; D015027:Zebrafish
chemical_list: C000716967:NPM1 protein, human; D009687:Nuclear Proteins; D009696:Nucleic Acids; D000090243:Nucleophosmin; D012313:RNA; D004247:DNA; C085108:APEX1 protein, human; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase