Humanizing Yeast

These baker’s yeast cells have genetic similarities to human cells. Credit: Rainis Venta

A billion years of evolution separate humans from the baker’s yeast in their refrigerators. But that didn’t stop a team led by Edward Marcotte, a professor in the Department of Molecular Biosciences, from demonstrating just how related the two distant cousins still are.

Marcotte’s team learned that hundreds of genes from a common ancestor of humans and yeast have remained nearly unchanged over the millenia. His experiment genetically engineering hundreds of strains of yeast with human genes demonstrated consistencies over time between the two. 

“It’s a beautiful demonstration of the common heritage of all living things—to be able to take DNA from a human and replace the matching DNA in a yeast cell and have it successfully support the life of the cell.”

Each strain received a single human gene swapped in for its yeast-gene counterpart. If the genes were too different, the yeast strain would die. Surprisingly, many gene groups were so stable over evolutionary time that becoming a little bit human with that single gene change made no difference. The yeast reproduced and thrived. Researchers found the yeast essentially couldn’t tell the difference between the two species’ genes with roughly half of the swaps.

 “Cells use a common set of parts and those parts, even after a billion years of independent evolution, are swappable,” says Marcotte, who holds the Corbin J. Robertson, Sr. Regents Chair in Molecular Biology. “It’s a beautiful demonstration of the common heritage of all living things—to be able to take DNA from a human and replace the matching DNA in a yeast cell and have it successfully support the life of the cell.” 

 The work has practical applications, as well. Partly humanized yeast could play a role in medical testing related to several genetic mutations and diseases.

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