A genus of yeast commonly found in grapes has lost a variety of genes known to keep cell division in line without any apparent consequences.
A team of researchers from Vanderbilt University in Tennessee analyzed 25 Hanseniaspora species genomes and identified two lineages, one of which evolved more rapidly. While both lineages lost a significant number of genes that are responsible for regulating the cell cycle and preserving genome, the one that evolved more rapidly lost most.
The findings published in the open-access journal PLOS Biology is surprising because, in humans, the same changes would lead to cancer.
Yeasts Evolving Fast
"It appears that, in genomic terms, Hanseniaspora are the yeast with the least," said Jacob L. Steenwyk, a graduate student at Vanderbilt and one of the authors of the study. "They have very small genomes and among the smallest numbers of genes of any species in the lineage."
Steenwyk's analysis estimated that the genomes of Hanseniaspora, which is also closely related to the baker's yeast Saccharomyces cerevisiae, might have lost hundreds of genes.
Antonis Rokas, the Cornelius Vanderbilt Chair in Biological Sciences, commented that the speed of the mutations is "unprecedented" and also "somewhat erratic." Due to the loss of the genes that regulate cell division and repair mutated DNA, the yeasts have experienced more changes in their DNA than other yeasts and have numerous genomic scars.
What Yeasts Can Teach About Cancer In Humans
The researchers noted that loss of these genes in humans can be the "hallmark of cancer."
"Some of the most commonly detected mutations in cancer-causing genes, or oncogenes, belong to the DNA repair pathway and cell cycle checkpoint pathways," explained Simon Conn of Flinders University in Australia who was not involved in the study.
The researchers added that the loss of hundreds of critical genes of the Hanseniaspora, an ancient lineage, could hold clues that can aid in the fight against cancer. Despite the absence of genes responsible for policing the rate at which genomes change, the yeasts have thrived for millions of years.
Conn suggested that the findings could lead to new therapies that target the DNA repair pathways.
