# Dissecting the Binding Interactions of the Chromatin Remodeler SMARCA4 with G‑Quadruplex DNA

## TL;DR

This study explores how the chromatin remodeler SMARCA4 interacts with G-quadruplex DNA structures, revealing specific binding preferences and mechanisms.

## Contribution

The study identifies the D1 helicase domain of SMARCA4 as the key region for G-quadruplex recognition and demonstrates its selective and prolonged binding.

## Key findings

- SMARCA4 selectively binds G-quadruplex DNA with low nanomolar affinities across various topologies.
- The D1 helicase domain of SMARCA4 is primarily responsible for G-quadruplex recognition.
- SMARCA4 exhibits longer residency times on G-quadruplex structures compared to other DNA interactions.

## Abstract

DNA G-quadruplexes
(G4s) are key structural features in chromatin
that are important to genome function. G4s have an apparent capacity
to recruit a wide variety of proteins, including chromatin remodelers,
yet the molecular basis and biophysical principles governing these
interactions remain poorly understood. Here, we sought to build insights
into the interactions of chromatin remodeler SMARCA4 with G4s using
a biophysical approach. We found that SMARCA4 selectively recognizes
the G4 structure over duplex and single-stranded DNA. SMARCA4 binds
a wide range of G4s with different topologies and loop lengths with
similar low nanomolar affinities. SMARCA4 was also observed to have
a longer residency time on the G4 structure compared to that of other
known protein–DNA interactions. We also found that the D1 (DExx-c)
helicase domain of SMARCA4, which is important for tethering SMARCA4
to chromatinized DNA, was the predominant binding domain for G4 recognition.
Our findings reveal new insights into how G4s interact with proteins,
which may have important implications for understanding G4-mediated
genome mechanisms.