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The yeast 2-micron plasmid Rep2 protein has Rep1-independent partitioning function
Anastasiia Mereshchuk1, Peter S Johnstone1, Joyce S K Chew1
1Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada.
Nucleic Acids Research
|September 26, 2022
Summary
The Rep2 protein, not Rep1, aids 2-micron plasmid partitioning in yeast by linking to a host factor. This Rep2 function is independent of the STB locus and the RSC2 complex, highlighting a novel role in plasmid inheritance.
Area of Science:
- * Molecular and Cellular Biology
- * Yeast Genetics
- * Epigenetics and Chromatin Dynamics
Background:
- * The 2-micron plasmid in *Saccharomyces cerevisiae* relies on Rep1 and Rep2 proteins for equal partitioning to daughter cells.
- * This partitioning involves the plasmid's STB locus and the host RSC2 complex, but the precise roles of Rep proteins remain unclear due to complex interactions.
Purpose of the Study:
- * To elucidate the specific contribution of Rep1 and Rep2 proteins to 2-micron plasmid partitioning.
- * To investigate the Rep protein-independent and STB-independent mechanisms of plasmid inheritance.
Main Methods:
- * Yeast genetics: Expression of Rep1 and Rep2 fused to the LexA DNA-binding domain in yeast strains with modified plasmids.
- * Plasmid transmission assays to quantify inheritance efficiency.
- * Deletion analysis of Rep2 to identify critical functional domains.
- * Site-directed mutagenesis of conserved motifs within Rep2.
Main Results:
- * Expression of Rep2-LexA fusion protein significantly increased plasmid transmission, independent of the STB locus and Rep1.
- * The C-terminal 65 residues of Rep2 were both necessary and sufficient for this Rep1-independent inheritance.
- * Mutation of a conserved basic motif within this Rep2 domain impaired both Rep1-independent and STB-dependent partitioning.
Conclusions:
- * Rep2 directly participates in 2-micron plasmid partitioning by interacting with a host component, facilitating efficient segregation.
- * This interaction is distinct from the previously understood Rep1/RSC2/STB-dependent pathway.
- * Further research is required to identify the specific host factor targeted by Rep2.
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