DisA Restrains the Processing and Cleavage of Reversed Replication Forks by the RuvAB-RecU Resolvasome

Area of Science:

• Molecular Biology
• Genetics
• Microbiology

Background:

• DNA replication forks can stall at DNA lesions, threatening genome stability.
• The Bacillus subtilis DisA protein plays a role in DNA repair and cell cycle regulation.
• The RuvAB-RecU complex is involved in resolving Holliday junctions during DNA repair.

Purpose of the Study:

• To investigate the role of DisA in managing stalled replication forks and its interaction with the RuvAB-RecU resolvasome.
• To determine how DisA influences DNA degradation and the synthesis of the c-di-AMP messenger.
• To elucidate the mechanism by which DisA preserves genome integrity during DNA damage response.

Main Methods:

• Biochemical assays to study protein-DNA interactions.
• Enzyme activity assays for DisA, RuvAB, and RecU.
• Analysis of DNA degradation and c-di-AMP synthesis in vitro.
• Investigating the effects of pre-bound complexes on enzyme activities.

Main Results:

• DisA interacts with stalled replication forks and pauses DisA at branched intermediates.
• Paused DisA suppresses c-di-AMP synthesis and prevents DNA degradation.
• DisA binds to Holliday junctions and reduces RuvAB ATPase activity.
• DisA pre-binding to Holliday junctions inhibits RuvAB and RecU, but not vice versa.

Conclusions:

• DisA acts as a crucial regulator at stalled replication forks, preventing DNA degradation and limiting potentially harmful fork remodeling.
• DisA's interaction with the RuvAB-RecU complex ensures timely DNA repair and replication restart, preserving genome integrity.
• DisA's modulation of c-di-AMP synthesis is linked to its role in DNA damage response and cell proliferation.