Yeast require redox switching in DNA primase.

O'Brien E, Salay LE, Epum EA, Friedman KL, Chazin WJ, Barton JK
Proc Natl Acad Sci U S A. 2018 115 (52): 13186-13191

PMID: 30541886 · PMCID: PMC6310810 · DOI:10.1073/pnas.1810715115

Eukaryotic DNA primases contain a [4Fe4S] cluster in the C-terminal domain of the p58 subunit (p58C) that affects substrate affinity but is not required for catalysis. We show that, in yeast primase, the cluster serves as a DNA-mediated redox switch governing DNA binding, just as in human primase. Despite a different structural arrangement of tyrosines to facilitate electron transfer between the DNA substrate and [4Fe4S] cluster, in yeast, mutation of tyrosines Y395 and Y397 alters the same electron transfer chemistry and redox switch. Mutation of conserved tyrosine 395 diminishes the extent of p58C participation in normal redox-switching reactions, whereas mutation of conserved tyrosine 397 causes oxidative cluster degradation to the [3Fe4S] species during p58C redox signaling. Switching between oxidized and reduced states in the presence of the Y397 mutations thus puts primase [4Fe4S] cluster integrity and function at risk. Consistent with these observations, we find that yeast tolerate mutations to Y395 in p58C, but the single-residue mutation Y397L in p58C is lethal. Our data thus show that a constellation of tyrosines for protein-DNA electron transfer mediates the redox switch in eukaryotic primases and is required for primase function in vivo.

Copyright © 2018 the Author(s). Published by PNAS.

MeSH Terms (10)

Crystallography, X-Ray DNA Primase Electron Transport Iron-Sulfur Proteins Models, Molecular Mutation Oxidation-Reduction Protein Conformation Saccharomyces cerevisiae Saccharomyces cerevisiae Proteins

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