Asymmetric DNA-search dynamics by symmetric dimeric proteins

Area of Science:

• Molecular Biology
• Biophysics
• Computational Biology

Background:

• Dimeric DNA-binding proteins, including transcription factors (TFs) and restriction endonucleases (REs), play crucial roles in cellular processes.
• Understanding how these proteins locate specific DNA sequences is fundamental to molecular biology.

Purpose of the Study:

• To investigate the mechanisms of one-dimensional (1D) sliding of dimeric TFs and REs along non-specific DNA.
• To elucidate how protein monomer interactions and DNA search strategies influence protein function.

Main Methods:

• Coarse-grained molecular dynamics simulations were employed to model DNA scanning by various TFs and REs.
• Analysis focused on parameters like sliding length, 1D/3D search partitioning, and diffusion coefficients under varying salt concentrations.

Main Results:

• Protein sliding characteristics, including efficiency, are highly dependent on salt concentration, influencing monomer cooperative mechanisms.
• Maximal DNA search efficiency is achieved via an asymmetric search mode where one monomer slides and the other hops.
• TFs demonstrate higher DNA affinity, longer sliding lengths, and a greater propensity for symmetric sliding than REs, functioning effectively over wider salt ranges.

Conclusions:

• Different biological functions of DNA-binding proteins correlate with distinct non-specific DNA search mechanisms.
• Asymmetric sliding is a key mechanism for efficient DNA searching, particularly for TFs.
• The distinct search strategies employed by TFs and REs explain their functional differences and adaptability to varying cellular environments.