Related Experiment Video

Updated: Jul 17, 2026

Generation of Marked and Markerless Mutants in Model Cyanobacterial Species
11:45

Generation of Marked and Markerless Mutants in Model Cyanobacterial Species

Published on: May 29, 2016

A mutant killer plasmid whose replication depends on a chromosomal "superkiller" mutation

A Toh-E1, R B Wickner

  • 1Laboratory of Biochemical Pharmacology, National Institute of Arthritis, Metabolism and Digestive Diseases, National Institutes of Health, Bethesda, Maryand 20014.

Genetics
|April 1, 1979
PubMed

Insights

Yeast killer plasmid variants ([KIL-sd]) require specific chromosomal mutations (ski) for replication. These ski-dependent plasmids are lost in normal yeast strains, revealing a novel form of mutagenesis.

Area of Science:

  • Molecular Biology
  • Yeast Genetics
  • Virology

Background:

  • Yeast strains with the killer plasmid (M dsRNA) produce a toxin lethal to non-carrier strains.
  • Chromosomal mutations in ski genes (ski1-ski4) enhance toxin production.

Purpose of the Study:

  • To characterize a novel killer plasmid mutation, [KIL-sd], dependent on chromosomal ski mutations for replication.
  • To investigate the interaction between killer plasmid variants and yeast chromosomal mutations.

Main Methods:

  • Introduction of wild-type killer plasmid ([KIL-k]) into ski mutant yeast strains.
  • Observation of killer plasmid stability and replication in different genetic backgrounds.
  • Analysis of killer plasmid conversion to the ski-dependent form ([KIL-sd]).

Main Results:

  • A ski-dependent killer plasmid ([KIL-sd]) was identified, requiring ski gene mutations for its maintenance.
  • [KIL-sd] plasmids are lost in wild-type (SKI+) yeast strains.
  • The wild-type killer plasmid ([KIL-k]) can convert to [KIL-sd] in specific ski mutant strains (e.g., ski2-2), suggesting mutagenesis or selective replication.
  • The ski2-3 mutation supports [KIL-sd] maintenance but does not induce conversion from [KIL-k].

Conclusions:

  • The [KIL-sd] plasmid lacks essential replication elements for wild-type yeast cells.
  • The ski mutations play a critical role in the replication and maintenance of specific killer plasmid variants.
  • The conversion of [KIL-k] to [KIL-sd] in ski mutants represents a unique phenomenon in yeast-plasmid interactions.

More Related Videos

Understanding the Development of Compensatory Pathways in a Mutant Malaria Parasite Harbouring Hypomorphic Allele of Plant-Like Kinases09:13

Understanding the Development of Compensatory Pathways in a Mutant Malaria Parasite Harbouring Hypomorphic Allele of Plant-Like Kinases

Published on: November 22, 2024

Related Concept Videos

Plasmids01:28

Plasmids

Plasmids are extrachromosomal DNA molecules found in bacteria, archaea, and some eukaryotic microbes like yeast. These small, circular DNA structures typically contain fewer than 30 genes, although some may exist linearly. Plasmids vary in their number within a cell, known as copy number. Single-copy plasmids are present in one copy per cell and multi-copy plasmids are present in multiple copies, reaching over 100 copies per cell.Plasmids usually replicate independently of the chromosomal DNA...
DNA Bacteriophages01:26

DNA Bacteriophages

Bacteriophages, or phages, are viruses that specifically infect bacteria, utilizing their genetic material to hijack host cellular machinery for replication. DNA bacteriophages employ single-stranded DNA (ssDNA) or double-stranded DNA (dsDNA) genomes. These phages exhibit diverse replication strategies and host interactions, influencing their ecological roles and applications in biotechnology and medicine.ssDNA BacteriophagesssDNA phages, with their small genomes, utilize unique strategies to...
Conservative Site-specific Recombination and Phase Variation02:53

Conservative Site-specific Recombination and Phase Variation

Because the DNA segments are cut and reorganized in a direction-specific manner, site-specific recombination has emerged as an efficient genetic engineering technique. Flippase and Cyclization recombinases or Flp and Cre, respectively, are two members of the tyrosine recombinase family derived from bacteriophages, that are used to mediate site-specific DNA insertions, deletions, and targeted expression of proteins in mammalian cell lines.
The recognition sites for Cre recombinase called LoxP...
The Replisome03:01

The Replisome

DNA replication is carried out by a large complex of proteins that act in a coordinated matter to achieve high-fidelity DNA replication. Together this complex is known as the DNA replication machinery or the replisome.
The synthesis of the leading and lagging strands is a highly coordinated process. To explain this, the “Trombone model” was proposed by Bruce Alberts in 1980. The DNA loop formation starts when a primer is synthesized on the parent lagging strand. The loop grows with the...