Prechemistry versus preorganization in DNA replication fidelity

Area of Science:

• Biochemistry
• Computational Biology
• Molecular Biology

Background:

• DNA polymerases are crucial for DNA replication and repair, ensuring genetic fidelity.
• Understanding nucleotide insertion mechanisms and fidelity is key to comprehending DNA replication accuracy.

Purpose of the Study:

• To explore the molecular origins of nucleotide insertion catalysis and DNA polymerase fidelity using computational simulations.
• To evaluate the roles of prechemistry effects, checkpoints, and dynamical effects in DNA polymerase fidelity.

Main Methods:

• Computational simulations, including free energy surface generation and potential of mean force (PMF) calculations.
• Analysis of X-ray structures of DNA polymerase beta (Pol β) complexes with correct (R) and incorrect (W) nucleotides.
• Application of the renormalization approach to examine dynamical effects.

Main Results:

• Simulations accurately reproduced the fidelity of Pol β.
• Potential of mean force calculations did not support significant prechemistry barriers.
• Dynamical effects and induced fit do not explain fidelity; fidelity arises from binding site relaxation.

Conclusions:

• DNA polymerase fidelity is primarily due to the altered preorganization of the catalytic site upon binding of an incorrect nucleotide.
• Prechemistry effects, checkpoints, and induced fit do not fully explain fidelity.
• The study clarifies the molecular basis of DNA polymerase accuracy and nucleotide selection.