1. Responses of DNA Mismatch Repair Proteins to a Stable G-Quadruplex Embedded into a DNA Duplex Structure.
- Author
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Pavlova AV, Monakhova MV, Ogloblina AM, Andreeva NA, Laptev GY, Polshakov VI, Gromova ES, Zvereva MI, Yakubovskaya MG, Oretskaya TS, Kubareva EA, and Dolinnaya NG
- Subjects
- Binding Sites, DNA Breaks, Double-Stranded, DNA, Bacterial chemistry, DNA, Bacterial metabolism, Escherichia coli metabolism, Escherichia coli Proteins genetics, Escherichia coli Proteins metabolism, MutL Proteins genetics, MutL Proteins metabolism, MutS DNA Mismatch-Binding Protein genetics, MutS DNA Mismatch-Binding Protein metabolism, Nucleotide Motifs, Protein Binding, Rhodobacter sphaeroides metabolism, DNA Mismatch Repair, DNA, Bacterial genetics, Escherichia coli genetics, G-Quadruplexes, Genome, Bacterial, Rhodobacter sphaeroides genetics
- Abstract
DNA mismatch repair (MMR) plays a crucial role in the maintenance of genomic stability. The main MMR protein, MutS, was recently shown to recognize the G-quadruplex (G4) DNA structures, which, along with regulatory functions, have a negative impact on genome integrity. Here, we studied the effect of G4 on the DNA-binding activity of MutS from Rhodobacter sphaeroides (methyl-independent MMR) in comparison with MutS from Escherichia coli (methyl-directed MMR) and evaluated the influence of a G4 on the functioning of other proteins involved in the initial steps of MMR. For this purpose, a new DNA construct was designed containing a biologically relevant intramolecular stable G4 structure flanked by double-stranded regions with the set of DNA sites required for MMR initiation. The secondary structure of this model was examined using NMR spectroscopy, chemical probing, fluorescent indicators, circular dichroism, and UV spectroscopy. The results unambiguously showed that the d(GGGT)
4 motif, when embedded in a double-stranded context, adopts a G4 structure of a parallel topology. Despite strong binding affinities of MutS and MutL for a G4, the latter is not recognized by E. coli MMR as a signal for repair, but does not prevent MMR processing when a G4 and G/T mismatch are in close proximity.- Published
- 2020
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