Mechanistic coupling of enzymatic activities at the replisome

DNA replication is a vital process requiring the synergistic coordination of enzymatic activities that include unwinding, priming, and synthesis. The helicase serves as the central hub of the replisome and maintains interactions with the enzymes involved in priming and synthesis, which can alter respective structural conformations to control kinetics. This review compares how evolutionarily diverse model systems from phage, Escherichia coli, and eukaryotes mechanistically couple these functions to maintain replication stability amid genomic challenges. Despite vast differences in complexity, all systems exhibit conserved principles of coordination through helicase-primase and helicase-polymerase interactions, facilitated by direct binding, intermediary proteins, or conformational constraints. We explore the structural and functional dynamics of replisome architecture, highlighting how core enzymes and accessory proteins collaborate to stabilize and regulate these complexes. Differences in replisome complexity, from the streamlined T7 to more intricate eukaryotic systems, underscore conserved and adaptive strategies for replication regulation. Consequences of replisome blocks leading to stalled forks or decoupled unwinding and synthesis, giving rise to single-strand gaps, are discussed in the context of conserved regulatory responses. Together, we provide insight into universal and divergent replisomal coupling mechanisms, offering a foundation for understanding replication-associated diseases and informing on novel therapeutic approaches.