title: SIRT6 protein deacetylase interacts with MYH DNA glycosylase, APE1 endonuclease, and Rad9-Rad1-Hus1 checkpoint clamp.
abstract: BACKGROUND
  SIRT6, a member of the NAD(+)-dependent histone/protein deacetylase family, regulates genomic stability, metabolism, and lifespan. MYH glycosylase and APE1 are two base excision repair (BER) enzymes involved in mutation avoidance from oxidative DNA damage. Rad9-Rad1-Hus1 (9-1-1) checkpoint clamp promotes cell cycle checkpoint signaling and DNA repair. BER is coordinated with the checkpoint machinery and requires chromatin remodeling for efficient repair. SIRT6 is involved in DNA double-strand break repair and has been implicated in BER. Here we investigate the direct physical and functional interactions between SIRT6 and BER enzymes.
  
  
  RESULTS
  We show that SIRT6 interacts with and stimulates MYH glycosylase and APE1. In addition, SIRT6 interacts with the 9-1-1 checkpoint clamp. These interactions are enhanced following oxidative stress. The interdomain connector of MYH is important for interactions with SIRT6, APE1, and 9-1-1. Mutagenesis studies indicate that SIRT6, APE1, and Hus1 bind overlapping but different sequence motifs on MYH. However, there is no competition of APE1, Hus1, or SIRT6 binding to MYH. Rather, one MYH partner enhances the association of the other two partners to MYH. Moreover, APE1 and Hus1 act together to stabilize the MYH/SIRT6 complex. Within human cells, MYH and SIRT6 are efficiently recruited to confined oxidative DNA damage sites within transcriptionally active chromatin, but not within repressive chromatin. In addition, Myh foci induced by oxidative stress and Sirt6 depletion are frequently localized on mouse telomeres.
  
  
  CONCLUSIONS
  Although SIRT6, APE1, and 9-1-1 bind to the interdomain connector of MYH, they do not compete for MYH association. Our findings indicate that SIRT6 forms a complex with MYH, APE1, and 9-1-1 to maintain genomic and telomeric integrity in mammalian cells.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 North Greene Street, Baltimore, MD, 21201, USA. BHwang@som.umaryland.edu.
authors.forename: Bor-Jang
authors.initials: BJ
authors.lastname: Hwang
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 North Greene Street, Baltimore, MD, 21201, USA. jinjin1681@yahoo.com.
authors.forename: Jin
authors.initials: J
authors.lastname: Jin
authors.affiliation: University of Pittsburgh Cancer Institute, University of Pittsburgh School of Medicine, 5117 Centre Avenue, Pittsburgh, PA, 15213, USA. yig10@pitt.edu.|School of Medicine, Tsinghua University, No.1 Tsinghua Yuan, Haidian District, Beijing, 100084, China. yig10@pitt.edu.
authors.forename: Ying
authors.initials: Y
authors.lastname: Gao
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 North Greene Street, Baltimore, MD, 21201, USA. gshi001@son.umaryland.edu.|University of Maryland School of Nursing, 655 West Lombard Street, Baltimore, MD, 21201, USA. gshi001@son.umaryland.edu.
authors.forename: Guoli
authors.initials: G
authors.lastname: Shi
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 North Greene Street, Baltimore, MD, 21201, USA. amadabushi@bccc.edu.|Department of Natural and Physical Sciences, Life Sciences Institute, Baltimore City Community College, 801 West Baltimore Street, Baltimore, MD, 21201, USA. amadabushi@bccc.edu.
authors.forename: Amrita
authors.initials: A
authors.lastname: Madabushi
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 North Greene Street, Baltimore, MD, 21201, USA. ay.savethetigers@gmail.com.
authors.forename: Austin
authors.initials: A
authors.lastname: Yan
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 North Greene Street, Baltimore, MD, 21201, USA. xin0709@yahoo.com.
authors.forename: Xin
authors.initials: X
authors.lastname: Guan
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 North Greene Street, Baltimore, MD, 21201, USA. MZalzman@som.umaryland.edu.|Department of Otorhinolaryngology-Head and Neck Surgery, University of Maryland School of Medicine, 16 South Eutaw Street, Baltimore, MD, 21201, USA. MZalzman@som.umaryland.edu.
authors.forename: Michal
authors.initials: M
authors.lastname: Zalzman
authors.affiliation: University of Pittsburgh Cancer Institute, University of Pittsburgh School of Medicine, 5117 Centre Avenue, Pittsburgh, PA, 15213, USA. san48@pitt.edu.|Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, 450 Technology Drive, Pittsburgh, PA, 15219, USA. san48@pitt.edu.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Nakajima
authors.affiliation: University of Pittsburgh Cancer Institute, University of Pittsburgh School of Medicine, 5117 Centre Avenue, Pittsburgh, PA, 15213, USA. lilyrisa2@gmail.com.|Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, 450 Technology Drive, Pittsburgh, PA, 15219, USA. lilyrisa2@gmail.com.
authors.forename: Li
authors.initials: L
authors.lastname: Lan
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 North Greene Street, Baltimore, MD, 21201, USA. alu-chang@som.umaryland.edu.|Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, 108 North Greene Street, Baltimore, MD, 21201, USA. alu-chang@som.umaryland.edu.
authors.forename: A-Lien
authors.initials: AL
authors.lastname: Lu
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D059447:Cell Cycle Checkpoints; D018797:Cell Cycle Proteins / Q000737:chemistry / Q000378:metabolism; D002843:Chromatin / Q000235:genetics; D004247:DNA / Q000378:metabolism*; D045647:DNA Glycosylases / Q000235:genetics / Q000378:metabolism; D004260:DNA Repair; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase / Q000235:genetics / Q000378:metabolism; D005092:Exonucleases / Q000378:metabolism; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D037761:Sirtuins / Q000235:genetics / Q000378:metabolism*; D016615:Telomere / Q000378:metabolism
chemical_list: D018797:Cell Cycle Proteins; D002843:Chromatin; C069930:rad9 protein; D004247:DNA; C501860:Sirt6 protein, mouse; D005092:Exonucleases; D045647:DNA Glycosylases; C061738:mutY adenine glycosylase; C516592:SIRT6 protein, human; D037761:Sirtuins; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase