The human GINS complex binds and specifically stimulates human DNA polymerase alpha/primase

The eukaryotic GINS complex has an essential role in theinitiation and elongation phases of genome duplication. It iscomposed of four paralogous subunits—Sld5, Psf1, Psf2 and Psf3—which are ubiquitous and evolutionarily conserved in eukaryotic organisms. Here, we report the biochemical characterization of the human GINS complex (hGINS). The four hGINS subunits were coexpressed in Escherichia coli in a highly soluble form and purified as a complex. hGINS was shown to interact directly with the heterodimeric human DNA primase, by using either surface plasmon resonance measurements or by immunoprecipitation experiments carried out with anti-hGINS antibodies. The DNA polymerase a-primase synthetic activity was specifically stimulated by hGINS on various primed DNA templates. The significance of these findings is discussed in view of the molecular dynamics at the human replication fork.