G4 resolvase 1 tightly binds and unwinds unimolecular G4-DNA.

Journal Article (Journal Article)

It has been previously shown that the DHX36 gene product, G4R1/RHAU, tightly binds tetramolecular G4-DNA with high affinity and resolves these structures into single strands. Here, we test the ability of G4R1/RHAU to bind and unwind unimolecular G4-DNA. Gel mobility shift assays were used to measure the binding affinity of G4R1/RHAU for unimolecular G4-DNA-formed sequences from the Zic1 gene and the c-Myc promoter. Extremely tight binding produced apparent K(d)'s of 6, 3 and 4 pM for two Zic1 G4-DNAs and a c-Myc G4-DNA, respectively. The low enzyme concentrations required for measuring these K(d)'s limit the precision of their determination to upper boundary estimates. Similar tight binding was not observed in control non-G4 forming DNA sequences or in single-stranded DNA having guanine-rich runs capable of forming tetramolecular G4-DNA. Using a peptide nucleic acid (PNA) trap assay, we show that G4R1/RHAU catalyzes unwinding of unimolecular Zic1 G4-DNA into an unstructured state capable of hybridizing to a complementary PNA. Binding was independent of adenosine triphosphate (ATP), but the PNA trap assay showed that unwinding of G4-DNA was ATP dependent. Competition studies indicated that unimolecular Zic1 and c-Myc G4-DNA structures inhibit G4R1/RHAU-catalyzed resolution of tetramolecular G4-DNA. This report provides evidence that G4R1/RHAU tightly binds and unwinds unimolecular G4-DNA structures.

Full Text

Duke Authors

Cited Authors

  • Giri, B; Smaldino, PJ; Thys, RG; Creacy, SD; Routh, ED; Hantgan, RR; Lattmann, S; Nagamine, Y; Akman, SA; Vaughn, JP

Published Date

  • September 1, 2011

Published In

Volume / Issue

  • 39 / 16

Start / End Page

  • 7161 - 7178

PubMed ID

  • 21586581

Pubmed Central ID

  • PMC3167620

Electronic International Standard Serial Number (EISSN)

  • 1362-4962

Digital Object Identifier (DOI)

  • 10.1093/nar/gkr234


  • eng

Conference Location

  • England