Crystal Structure and Deletion Analysis Show that the Accessory Subunit of Mammalian DNA Polymerase γ, PolγB, Functions as a Homodimer

By J. Carrodeguas, Karsten Theis, D. Bogenhagen, C. Kisker. 2001

143 citations recorded by the source corpus.

Abstract Polymerase γ, which replicates and repairs mitochondrial DNA, requires the PolγB subunit for processivity. We determined the crystal structure of mouse PolγB, a core component of the mitochondrial replication machinery. PolγB shows high similarity to glycyl-tRNA synthetase and dimerizes through an unusual intermolecular four-helix bundle. A human PolγB mutant lacking the four-helix bundle failed to dimerize in solution or to stimulate the catalytic subunit PolγA, but retained the ability to bind with PolγA to a primer–template construct, indicating that the functional holoenzyme contains two PolγB molecules. Other mutants retained stimulatory activity but lost the ability to bind folded ssDNA. These results suggest that the PolγB dimer contains distinct sites for PolγA binding, dimerization, and DNA binding.

Subfields: Molecular Biology

View Paper: https://www.semanticscholar.org/paper/73d7282a8e4e14102663f9d9a16d626e2d39803b

Citations in the corpus

• Mitochondrial transcription factors B1 and B2 activate transcription of human mtDNA (2002, unknown): “Notably, the crystal structure of the accessory subunit of the mitochondrial DNA polymerase shows that this protein has strong structural similarity to aminoacyl tRNA synthetase”