Pif1 family helicases promote mutation avoidance during DNA replication

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• Pif1 family 5' → 3' DNA helicases are essential for DNA replication and maintaining genome stability.
• The budding yeast Saccharomyces cerevisiae has two Pif1 helicases: Rrm3 and Pif1, with known multiple functions.

Purpose of the Study:

• To investigate novel functions of Rrm3 in preventing mutations during DNA replication.
• To understand the role of Rrm3 in DNA polymerase fidelity and its impact on genome-wide mutagenesis.

Main Methods:

• Utilized genome-wide analysis to assess mutational consequences in yeast lacking RRM3.
• Investigated the dependency of mutation avoidance on Rrm3's helicase activity.

Main Results:

• Loss of RRM3 leads to increased spontaneous mutations by DNA polymerases Pol ε and δ, and Pol ζ.
• Rrm3's mutation avoidance function is locus-dependent and particularly vital for suppressing Pol ζ mutagenesis at tRNA genes.
• Rrm3's role in mutation avoidance requires its helicase activity, with Pif1 acting as a backup.

Conclusions:

• Rrm3 actively promotes DNA replication fidelity across the genome, especially at tRNA genes.
• The function of Pif1 family helicases in mutation avoidance appears evolutionarily conserved, potentially contributing to tumor suppression.