Related Experiment Video
Updated: Aug 14, 2026
Genetic Screen for Identification of Multicopy Suppressors in Schizosaccharomyces pombe
Published on: September 13, 2022
The wild-type Schizosaccharomyces pombe mat1 imprint consists of two ribonucleotides
Sonya Vengrova1, Jacob Z Dalgaard
1Marie Curie Research Institute, The Chart, Oxted, Surrey, UK.
Abstract:
The imprint at the mat1 locus of Schizosaccharomyces pombe acts to initiate the replication-coupled recombination event that underlies mating-type switching. However, the nature of the imprint has been an area of dispute. Two alternative models have been proposed: one stated that the imprint is a nick in the DNA, whereas our data suggested that it consists of one or two ribonucleotides incorporated into the otherwise intact DNA duplex. Here, we verify key predictions of the RNA model by characterization of wild-type genomic DNA purified under conditions known to hydrolyse DNA-RNA-DNA hybrid strands. First, we observe one-nucleotide gap at the hydrolysed DNA, as expected from the presence of two ribonucleotides. Second, using a novel assay based on ligation-mediated PCR, a 3'-terminal ribonucleotide is detected at the hydrolysed imprint. Our observations allow the unification of available data sets characterizing the wild-type imprint.
Insights
The mating-type switching imprint in fission yeast is not a DNA nick, but rather one or two ribonucleotides within the DNA. This finding clarifies the mechanism initiating replication-coupled recombination.
Area of Science:
- Molecular Biology
- Genetics
- Yeast Biology
Background:
- The mat1 locus imprint in Schizosaccharomyces pombe initiates mating-type switching via replication-coupled recombination.
- The precise molecular nature of this imprint has been debated, with models proposing either a DNA nick or ribonucleotides.
Purpose of the Study:
- To definitively characterize the molecular composition of the wild-type mat1 locus imprint.
- To resolve the dispute between the DNA nick and ribonucleotide models.
Main Methods:
- Purification of wild-type genomic DNA under conditions that hydrolyze DNA-RNA-DNA hybrids.
- Analysis of DNA structure using ligation-mediated PCR to detect terminal modifications.
Main Results:
- Hydrolysis revealed a one-nucleotide gap, consistent with the presence of two ribonucleotides.
- A novel ligation-mediated PCR assay detected a ribonucleotide at the 3' end of the hydrolyzed imprint.
Conclusions:
- The results strongly support the model where the imprint consists of one or two ribonucleotides within an intact DNA duplex.
- This characterization unifies previous disparate data sets regarding the wild-type imprint's nature.
More Related Videos
08:07Analysis of the Expression and Complexes Assembly of the Mitochondrial Respiratory Chain Proteins in the Fission Yeast Schizosaccharomyces pombe
Published on: May 2, 2025
07:55A Deep-sequencing-assisted, Spontaneous Suppressor Screen in the Fission Yeast Schizosaccharomyces pombe
Published on: March 7, 2019
Related Concept Videos
02:30Genomic Imprinting and Inheritance
The expression of some genes depends on which parent passed the gene to the offspring, through a phenomenon known as...
02:57piRNA - Piwi-interacting RNAs
01:20Mismatch Repair
The Mutator Protein Family Plays a Key Role in DNA Mismatch Repair
The human genome has more than 3 billion base pairs of DNA per cell. Prior to cell division, that vast amount of genetic...
01:36Mismatch Repair
02:53Ribosomal RNA Synthesis
Ribosome biogenesis begins with the synthesis of 5S and 45S pre-rRNAs by distinct RNA polymerases. The primary transcripts are extensively processed and modified before they are bound and folded by ribosomal proteins and assembly factors,...
02:53Ribosomal RNA Synthesis
Ribosome biogenesis begins with the synthesis of 5S and 45S pre-rRNAs by distinct RNA polymerases. The primary transcripts are extensively processed and modified before they are bound and folded by ribosomal proteins and assembly factors,...