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1G5I: Crystal Structure Of The Accessory Subunit Of Murine Mitochondrial Polymerase Gamma
Crystal structure and deletion analysis show that the accessory subunit of mammalian DNA polymerase gamma, Pol gamma B, functions as a homodimer
Mol. Cell (2001) 7 p.43-54» All references (2)
Polymerase gamma, which replicates and repairs mitochondrial DNA, requires the Pol gamma B subunit for processivity. We determined the crystal structure of mouse Pol gamma B, a core component of the mitochondrial replication machinery. Pol gamma B shows high similarity to glycyl-tRNA synthetase and dimerizes through an unusual intermolecular four-helix bundle. A human Pol gamma B mutant lacking the four-helix bundle failed to dimerize in solution or to stimulate the catalytic subunit Pol gamma A, but retained the ability to bind with Pol gamma A to a primer-template construct, indicating that the functional holoenzyme contains two Pol gamma B molecules. Other mutants retained stimulatory activity but lost the ability to bind folded ssDNA. These results suggest that the Pol gamma B dimer contains distinct sites for Pol gamma A binding, dimerization, and DNA binding.