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Characterization of Interaction of the MBP-Tagged MuRif1-C-Terminal Domain with G-Quadruplex DNA by SPR

Hamed Ghadiri1,a, Sana Alavi2,b, Bahareh Dabirmanesh1,c, and Khosro Khajeh1,2,d*

1Department of Biochemistry, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran

2Department of Nanobiotechnology, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran

* To whom correspondence should be addressed.

Received November 11, 2020; Revised June 6, 2021; Accepted June 7, 2021
One of the main players in the cell-specific replication timing pattern is Rap1 interacting factor-1 (Rif1). Rif1 protein consists of N-terminal and C-terminal domains and an intrinsically disordered region in between. It has been suggested that both N- and C-termini of Rif1 are capable of binding to DNA with particularly high affinity to cruciform DNA structures. In the present study, we expressed, solubilized, and purified the maltose-binding protein-tagged murine Rif1 C-terminal domain (MBP-muRif1-CTD). Biological activity of the purified protein was assessed by the electrophoretic mobility shift assay (EMSA) and surface plasmon resonance (SPR). Our results show that the MBP-muRif1-CTD binds G-quadruplex (G4) structure with high affinity (KD 19.0 ± 0.8 nM), as was previously suggested. This study is the first step in investigation of the interaction of MBP-Profinity eXact-muRif1-CTD and G4 by SPR.
KEY WORDS: murine Rap1 interacting factor 1 (muRif1), surface plasmon resonance, maltose-binding protein (MBP), G-Quadruplex (G4), gel shift assay

DOI: 10.1134/S0006297921070105