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Crystal structure of the heterotrimeric PriSLX primase from S. solfataricus.
Structural highlights
FunctionPRIS_SACS2 Catalytic subunit of DNA primase, an RNA polymerase that catalyzes the synthesis of short RNA molecules used as primers for DNA polymerase during DNA replication. The small subunit contains the primase catalytic core and has DNA synthesis activity on its own. Binding to the large subunit stabilizes and modulates the activity, increasing the rate of DNA synthesis while decreasing the length of the DNA fragments, and conferring RNA synthesis capability. The DNA polymerase activity may enable DNA primase to also catalyze primer extension after primer synthesis. May also play a role in DNA repair. Possesses a template-independent 3'-terminal nucleotidyl transferase activity.[HAMAP-Rule:MF_00700][1] Publication Abstract from PubMedDNA replication depends on primase, the specialised polymerase responsible for synthesis of the RNA primers that are elongated by the replicative DNA polymerases. In eukaryotic and archaeal replication, primase is a heterodimer of two subunits, PriS and PriL. Recently, a third primase subunit named PriX was identified in the archaeon Sulfolobus solfataricus. PriX is essential for primer synthesis and is structurally related to the Fe-S cluster domain of eukaryotic PriL. Here we show that PriX contains a nucleotide-binding site required for primer synthesis, and demonstrate equivalence of nucleotide-binding residues in PriX with eukaryotic PriL residues that are known to be important for primer synthesis. A primase chimera, where PriX is fused to a truncated version of PriL lacking the Fe-S cluster domain retains wild-type levels of primer synthesis. Our evidence shows that PriX has replaced PriL as the subunit that endows primase with the unique ability to initiate nucleic acid synthesis. Importantly, our findings reveal that the Fe-S cluster is not required for primer synthesis. Primer synthesis by a eukaryotic-like archaeal primase is independent of its Fe-S cluster.,Holzer S, Yan J, Kilkenny ML, Bell SD, Pellegrini L Nat Commun. 2017 Nov 23;8(1):1718. doi: 10.1038/s41467-017-01707-w. PMID:29167441[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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