The archaeo-eukaryotic GINS proteins and the archaeal primase catalytic subunit PriS share a common domain

Primase and GINS are essential factors for chromosomal DNA replication in eukaryotic and archaeal cells. Here we describe a previously undetected relationship between the C-terminal domain of the catalytic subunit (PriS) of archaeal primase and the B-domains of the archaeo-eukaryotic GINS proteins in the form of a conserved structural domain comprising a three-stranded antiparallel β-sheet adjacent to an α-helix and a two-stranded β-sheet or hairpin. The presence of a shared domain in archaeal PriS and GINS proteins, the genes for which are often found adjacent on the chromosome, suggests simple mechanisms for the evolution of these proteins. REVIEWERS: This article was reviewed by Zvi Kelman (nominated by Michael Galperin) and Kira Makarova.