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Mutational Dissection of Telomeric DNA Binding Requirements of G4 Resolvase 1 Shows that G4-Structure and Certain 3'-Tail Sequences Are Sufficient for Tight and Complete Binding.
Smaldino, Philip J; Routh, Eric D; Kim, Jung H; Giri, Banabihari; Creacy, Steven D; Hantgan, Roy R; Akman, Steven A; Vaughn, James P.
Afiliação
  • Smaldino PJ; Department of Cancer Biology, Wake Forest School of Medicine, Winston-Salem, North Carolina, 27157, United States of America.
  • Routh ED; Department of Cancer Biology, Wake Forest School of Medicine, Winston-Salem, North Carolina, 27157, United States of America.
  • Kim JH; Department of Cancer Biology, Wake Forest School of Medicine, Winston-Salem, North Carolina, 27157, United States of America.
  • Giri B; Department of Chemistry, Furman University, Greenville, South Carolina, 29613, United States of America.
  • Creacy SD; Department of Cancer Biology, Wake Forest School of Medicine, Winston-Salem, North Carolina, 27157, United States of America; Harmonyx Diagnostics, Cordova, Tennessee, 38016, United States of America.
  • Hantgan RR; Department of Biochemistry, Wake Forest School of Medicine, Winston-Salem, North Carolina, 27157, United States of America.
  • Akman SA; Department of Hematology and Oncology, Roper St. Francis Hospital, Charleston, South Carolina, 29401, United States of America.
  • Vaughn JP; Department of Cancer Biology, Wake Forest School of Medicine, Winston-Salem, North Carolina, 27157, United States of America.
PLoS One ; 10(7): e0132668, 2015.
Article em En | MEDLINE | ID: mdl-26172836
Ends of human chromosomes consist of the six nucleotide repeat d[pTTAGGG]n known as telomeric DNA, which protects chromosomes. We have previously shown that the DHX36 gene product, G4 Resolvase 1 (G4R1), binds parallel G-quadruplex (G4) DNA with an unusually tight apparent Kd. Recent work associates G4R1 with the telomerase holoenzyme, which may allow it to access telomeric G4-DNA. Here we show that G4R1 can tightly bind telomeric G4-DNA, and in the context of the telomeric sequence, we determine length, sequence, and structural requirements sufficient for tight G4R1 telomeric binding. Specifically, G4R1 binds telomeric DNA in the K+-induced "3+1" G4-topology with an apparent Kd = 10 ± 1.9 pM, a value similar as previously found for binding to unimolecular parallel G4-DNA. G4R1 binds to the Na+-induced "2+2" basket G4-structure formed by the same DNA sequence with an apparent Kd = 71 ± 2.2 pM. While the minimal G4-structure is not sufficient for G4R1 binding, a 5' G4-structure with a 3' unstructured tail containing a guanine flanked by adenine(s) is sufficient for maximal binding. Mutations directed to disrupt G4-structure similarly disrupt G4R1 binding; secondary mutations that restore G4-structure also restore G4R1 binding. We present a model showing that a replication fork disrupting a T-loop could create a 5' quadruplex with an opened 3'tail structure that is recognized by G4R1.
Assuntos

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: DNA / RNA Helicases DEAD-box / Quadruplex G Limite: Humans Idioma: En Ano de publicação: 2015 Tipo de documento: Article

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: DNA / RNA Helicases DEAD-box / Quadruplex G Limite: Humans Idioma: En Ano de publicação: 2015 Tipo de documento: Article