Bridging DNA contacts allow Dps from E. coli to condense DNA

Area of Science:

• Microbiology
• Biochemistry
• Molecular Biology

Background:

• The DNA-binding protein from starved cells (Dps) is vital for bacterial survival under stress.
• Dps interacts with DNA to form biomolecular condensates in vivo and in vitro.
• The precise mechanism of Dps-DNA complex nucleation on DNA is not fully understood.

Purpose of the Study:

• To investigate the influence of DNA topology on the formation of Dps-DNA complexes.
• To elucidate the role of DNA structure in Dps complex nucleation and stabilization.

Main Methods:

• In vitro experiments combining purified Dps protein with DNA.
• Analysis of Dps complex formation on DNA with varying topological states (supercoiled vs. linear/relaxed).

Main Results:

• DNA supercoils serve as the preferred template for Dps complex nucleation.
• Bridging contacts between DNA regions significantly facilitate Dps condensation.
• Dps exhibits low affinity for relaxed, stretched DNA prior to condensation.
• Condensed Dps-DNA complexes are stable and can maintain inter-strand DNA contacts without free Dps.

Conclusions:

• DNA topology, particularly supercoiling and bridging contacts, is critical for initiating Dps-DNA complex formation.
• These DNA structural features are essential for both the nucleation and stabilization of Dps complexes.
• Understanding these interactions provides insight into bacterial stress response mechanisms.