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Updated: Aug 7, 2026

Proofreading and DNA Repair Assay Using Single Nucleotide Extension and MALDI-TOF Mass Spectrometry Analysis
Published on: June 19, 2018
Mutations in conserved yeast DNA primase domains impair DNA replication in vivo
S Francesconi1, M P Longhese, A Piseri
1Dipartimento di Genetica e di Biologia dei Microrganismi, Milano, Italy.
Abstract:
To assess the role of eukaryotic DNA primase in vivo, we have produced conditional and lethal point mutations by random in vitro mutagenesis of the PR11 and PR12 genes, which encode the small and large subunits of yeast DNA primase. We replaced the wild-type copies of PRI1 and PRI2 with two pri1 and two pri2 conditional alleles. When shifted to the restrictive temperature, these strains showed altered DNA synthesis and reduced ability to synthesize high molecular weight DNA products, thus providing in vivo evidence for the essential role of DNA primase in eukaryotic DNA replication. Furthermore, mapping of the mutations at the nucleotide level has shown that the two pri1 and two pri2 conditional alleles and one pri2 lethal allele have suffered single base-pair substitutions causing a change in amino acid residues conserved in the corresponding mouse polypeptide.
Insights
This study demonstrates the essential role of eukaryotic DNA primase in DNA replication. Conditional mutations in yeast DNA primase genes confirmed its necessity for synthesizing high molecular weight DNA products in vivo.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- Eukaryotic DNA primase is crucial for initiating DNA replication.
- Understanding its in vivo function is essential for comprehending replication fidelity and mechanisms.
Purpose of the Study:
- To investigate the in vivo role of eukaryotic DNA primase.
- To generate and characterize conditional and lethal mutations in yeast DNA primase subunits.
Main Methods:
- Random in vitro mutagenesis of PR11 and PR12 genes encoding yeast DNA primase subunits.
- Replacement of wild-type genes with conditional alleles (pri1 and pri2).
- Analysis of DNA synthesis and product formation at restrictive temperatures.
Main Results:
- Conditional yeast strains exhibited altered DNA synthesis upon temperature shift.
- Reduced ability to synthesize high molecular weight DNA products was observed.
- Nucleotide-level mapping revealed conserved amino acid residue changes in mutated subunits.
Conclusions:
- This study provides in vivo evidence for the essential function of DNA primase in eukaryotic DNA replication.
- Mutations affecting conserved amino acid residues highlight critical functional domains of DNA primase.
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