Kinetic modelling of DNA replication initiation in budding yeast

Area of Science:

• Cell Biology
• Molecular Biology
• Systems Biology

Background:

• DNA replication is a critical cell cycle process, restricted to S phase, requiring precise regulation for accurate genome duplication.
• Existing mathematical models of cell cycle networks often overlook the intricate steps of DNA replication initiation.
• The assembly and activation of the pre-replicative complex (pre-RC) and pre-initiation complex (pre-IC) are crucial for initiating DNA replication.

Purpose of the Study:

• To develop a mathematical model simulating the network controlling DNA replication initiation in budding yeast.
• To investigate the roles of cyclin-dependent kinases (CDKs) and Dbf-dependent kinase (DDK) in regulating pre-RC and pre-IC formation.
• To computationally verify the dynamics of replication machinery assembly against existing literature data.

Main Methods:

• Developed an Ordinary Differential Equation (ODE)-based model utilizing mass-action kinetics.
• Modeled all steps from initial component assembly at replication origins to the formation of the active replisome.
• Validated computational dynamics with data from available scientific literature.

Main Results:

• The model highlights a direct link between the activation of CDK and DDK and the sequential formation of pre-RC and pre-IC.
• Results suggest that S-CDK (Cdk1-Clb5,6) plays a pivotal role as the primary regulator of DNA replication initiation.
• The computational dynamics accurately reflect step-by-step complex formation as described in the literature.

Conclusions:

• The study provides a mechanistic model for DNA replication initiation, emphasizing the coordinated action of kinases.
• S-CDK is identified as a key regulator controlling the transition from pre-RC to pre-IC, ensuring timely S phase progression.
• This modeling approach offers insights into the complex biochemical networks governing cell cycle progression and genome stability.