Archaeal primase: bridging the gap between RNA and DNA polymerases

In the evolution of life, DNA replication is a fundamental process, by whic h species transfer their genetic information to their offspring. DNA polyme rases, including bacterial and eukaryotic replicases, are incapable of de n ovo DNA synthesis, DNA primases are required for this function, which is si ne qua non to DNA replication. In Escherichia coli, the DNA primase (DnaG) exists as a monomer and synthesizes a short RNA primer. In Eukarya, however , the primase activity resides within the DNA polymerase alpha -primase com plex (Pol alpha -pri) on the p48 subunit, which synthesizes the short RNA s egment of a hybrid RNA-DNA primer. To date, Very little information is avai lable regarding the priming of DNA replication in organisms in Archaea, Ava ilable sequenced genomes indicate that the archaeal DNA primase is a homolo g of the eukaryotic p48 subunit, Here, we report investigations of a p48-li ke DNA primase from Pyrococcus furiosus, a hyperthermophilic euryarchaeote. P, furiosus p48-like protein (Pfup41), unlike hitherto-reported primases, does not catalyze by itself the synthesis of short RNA primers but preferen tially utilizes deoxynucleotides to synthesize DNA fragments up to several kilobases in length, Pfup41 is the first DNA polymerase that does not requi re primers for the synthesis of long DNA strands.