How selfish genes succeed: Research on selfish genes provides new insight on meiotic drive systems

New findings from the Stowers Institute for Medical Research uncover critical insights about how a dangerous selfish gene — considered to be a parasitic portion of DNA — functions and survives. Understanding this dynamic is a valuable resource for the broader community studying meiotic drive systems.

A new study, published in PLoS Genetics on Dec. 7, 2022, reveals how a selfish gene in yeast uses a poison-antidote strategy that enables its function and likely has facilitated its long-term evolutionary success. This strategy is an important addition for scientists studying similar systems including teams that are designing synthetic drive systems for pathogenic pest control. Collective and collaborative advancement on understanding drive may one day lead to the eradication of pest populations that harm crops or even humans in the case of vector borne diseases.

“It’s quite dangerous for a genome to encode a protein that has the capacity to kill the organism,” said Stowers Associate Investigator SaraH Zanders, Ph.D. “However, understanding the biology of these selfish elements could help us build synthetic drivers to modify natural populations.”

Drivers are selfish genes that can spread in a population at higher rates than most other genes, without benefiting the organism. Previous research from the Zanders Lab revealed that a driver gene in yeast, wtf4, produces poison protein capable of destroying all offspring. However, for a given parent cell’s chromosome pair, drive is achieved when wtf4 is found only on one chromosome. The effect is a simultaneous rescue of only those offspring that inherit the drive allele, by delivering a dose of a very similar protein that counteracts the poison, the antidote.

Building upon this work, the study, led by former Predoctoral Researcher Nicole Nuckolls, Ph.D., and current Predoctoral Researcher Ananya Nidamangala Srinivasa in the Zanders Lab, discovered that differences in the timing of generating poison and antidote proteins from wtf4 and their unique distribution patterns within developing spores are fundamental to the drive process.

The team has developed a model they are continuing to investigate for how the poison acts to kill the spore — the equivalent of a human egg or sperm in yeast. Their results indicate that poison proteins cluster together, potentially disrupting proper folding of other proteins required for the cell to function. Because the wtf4 gene encodes both poison and antidote, the antidote is very similar in form and groups together with the poison. However, the antidote has an extra part that appears to isolate the poison-antidote clusters by bringing them to the cell’s garbage can, the vacuole.

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