Stimulation of DNA polymerase gamma by a mitochondrial single-strand DNA binding protein.

A Single-strand DNA binding protein was purified to homogeneity from mitochondria of HeLa cells. The purified protein consists of two polypeptides with molecular weights of 15.5 and 16 KDA. The protein binds single-strand DNA and stimulates purified DNA polymerase gamma in a primer extension assay. Stimulation of DNA polymerase gamma is highly specific, as no effect was detected on bacterial or nuclear DNA polymerases. The single-strand DNA binding protein is therefore likely to be an essential component for the replication of mitochondrial DNA. We have provided evidence that there exist other additional accessory components that are required for processive action of DNA polymerase gamma.