STIMULATION OF DNA-POLYMERASE-GAMMA BY A MITOCHONDRIAL SINGLE-STRAND DNA-BINDING PROTEIN

A Single-strand DNA binding protein was purified to homogeneity from m itochondria of HeLa cells. The purified protein consists of two polype ptides with molecular weights of 15.5 and 16 KDA. The protein binds si ngle-strand DNA and stimulates purified DNA polymerase gamma in a prim er extension assay. Stimulation of DNA polymerase gamma is highly spec ific, as no effect was detected on bacterial or nuclear DNA polymerase s. 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 componen ts that are required for processive action of DNA polymerase gamma.