Mark Johnston is quick to explain that his fascination with yeast is nothing new when considered in the larger framework of human history.
It boils down to how yeast, as a single-celled organism, processes sugar, insists Johnston, a professor and chairman of the University of Colorado School of Medicine’s Department of Biochemistry and Molecular Genetics. Unlike humans, who break glucose down in order to produce molecules that can be used as energy, yeast takes a different approach to sugars. It’s a trait that’s made the stuff an important staple in the development of human culture, civilization and history.
“Yeast does something very different. When it sees glucose, it doesn’t burn it. Instead, it ferments it,” Johnston said. “The end products of that fermentation for yeast are ethanol and carbon dioxide. The CO2 is what raises bread and gives beer its fizzy quality. The ethanol is what spices the beverages … Humans discovered that 6,000 years ago and have been using it ever since.”
Johnston doesn’t have quite as long a track record with the substance as that, but his scientific inquiries and research related to yeast do stretch back decades. From his work in graduate school in the late 1970s to his seminal work on genome sequencing projects and developing genome-wide resources for yeast research, Johnston has spent years searching for the material’s deeper, microscopic secrets.
“Yeast is in the same kingdom of life as humans are. Much of what we know of human function comes from the study of organisms like yeast,” Johnston said. “The particular area I’m interested in is nutrient sensing. I’ve always been amazed that these small single celled organisms can sense their environment.”
Johnston’s careful research and groundbreaking discoveries haven’t gone unnoticed by his peers. He moved from his longtime post at Washington University in St. Louis to the University of Colorado’s Aurora campus three years ago to spearhead research and technological development in the school’s biochemistry and molecular genetics department.
More recently, Johnston got a big nod from a national organization, earning a spot in the 2012 class of the American Academy of Arts and Sciences. Johnston was elected as part of the Academy’s cellular and developmental biology, microbiology and immunology section, along with nine other high-profile scientists from across the country. The total class of 220 inductees includes plenty of honorees whose fields of expertise are far removed from the lab. Secretary of State Hillary Rodham Clinton, philanthropist Melinda Gates, film star Clint Eastwood, comedian Mel Brooks and former Beatle Paul McCartney have all been named as this year’s class.
“Election to the Academy is both an honor for extraordinary accomplishment and a call to serve,” Academy President Leslie C. Berlowitz said in a release from the University of Colorado. “We look forward to drawing on the knowledge and expertise of these distinguished men and women to advance solutions to the pressing policy challenges of the day.”
For Johnston, inclusion in a class that includes modern scientific luminaries like chemist James Fraser Stoddart, oncologist Brian Druker and Griffin P. Rodgers, the director of the National Institute of Diabetes and Digestive and Kidney Diseases, is a highlight of a career that features plenty of firsts.
“This is the highest honor that I’ve ever gotten. I’ve gotten a few other elections, but this is a bigger deal,” said Johnston, who will travel to Massachusetts in October for the formal induction ceremony. “Scientists are patting themselves on the back all the time, you know these things are possible. But I just learned a few days ago. I was pleased,” he added.
Johnston said he suspects the recognition came largely from his work on genome sequencing in the 1990s, efforts that were part of a worldwide push that included more than 100 labs.
“Back in the early 90s, all of that stuff was new. It turns out that yeast was the first ukaryotic organism to have its genome sequence determined,” Johnston said. “Back then it was hard to sequence DNA, so the project tackled organisms that had smaller genomes … I played a big role in that. It was a distributed international project to sequence the yeast genome. I played a big part in the U.S. aspect.”
Having a key role in the early days of the sequencing efforts has helped put the technological advances of the past decade into perspective for Johnston, who counts himself as lucky to have entered the field at the perfect moment.
Reach reporter Adam Goldstein at agoldstein@aurorasentinel.com or 720-449-9707