“Chance favors the prepared mind.” –Louis Pasteur
Matan received his B.S. in Pharmacology from the University of California, Santa Barbara. After graduating, he moved to Indiana University where he is currently working on his Ph.D. in the lab of Stephen D. Bell working on DNA replication in archaea. Matan’s thesis project involves dissecting the biochemical mechanism of primase function, as well as studying the composition of the active replication machine, termed the replisome.
All cellular organisms require accurate and efficient replication of their genomes by DNA Polymerases (DNAPs); however, DNAPs cannot initiate replication without the action of a specialized DNA dependent RNA Polymerase termed primase. Primase synthesizes a short RNA molecule known as the primer. Biochemical constraints on the polymerase combined with the antiparallel nature of DNA presents a formidable challenge at the replication fork. One strand continuously replicates in the direction of fork opening while the other strand must undergo cycles of priming and short synthesis in the direction opposite to fork progression. Throughout evolution two classes of primases have separately evolved: single subunit bacterial DnaG and archaeal/eukaryotic PriS:PriL core. PriS is responsible for RNA synthesis and PriL is thought to have a regulatory function. Interestingly, a conserved Iron-Sulfur (FeS) cluster exists within the PriL C-terminal domain whose function remains poorly understood. FeS clusters have recently been shown to be components of many DNA associated proteins, and are able to undergo redox chemistry. The primase complex in Sulfolobus solfataricus is made up of PriS, PriL, and a recently found accessory subunit PriX. Here we investigate the FeS cluster within PriL and the effects of PriX on complex function. We show that PriX enhances the primase activity of the complex significantly. In addition, PriX stabilizes the FeS cluster. Importantly, however, we show that FeS cluster stability is not required for complex formation or primase activity in vitro. Finally, we uncovered a primase concentration dependence governing primer length with primers corresponding to the in vivo length only being synthesized in the presence of excess primase.