Fig. 6: Strand displacement mechanism in DNAPs of the Pol A family.
From: Structural basis for intrinsic strand displacement activity of mitochondrial DNA polymerase
A Strand separation in mitochondrial RNAP (left) and DNAP (right). Polymerases were aligned using the conserved catalytic residues in their palm subdomains. Note the nearly identical trajectory of the RNA-DNA and the primer-template duplexes in both structures. B–E Conservation of the SD loop in DNAPs of the Pol A family. Polγ – human mitochondrial DNAP, T7 – bacteriophage T7 DNAP, TAQ - Thermus aquaticus DNAP, BST – Geobacillus stearothermophilus DNAP. F–I Catcher loop insertion into the conserved fingers domain of DNAPs of the Pol A family. Helices O2 and P are indicated. The Catcher loop in human Polγ is modeled using AlphaFold3. Mitochondrial DNA polymerases use different mechanisms for strand separation during replication. Here, the authors reveal the cryo-EM structures of yeast Mip1, identifying key structural elements that enable strand displacement. Mutations in these elements impair mitochondrial function and DNA maintenance.
