Reposted from the College of Science.

Pictured above: Mary Fairbanks, who graduated in 2023 with a B.S. in biology.

Most life forms on Earth possess systems to repair damaged DNA, while some microorganisms have evolved an intriguing strategy that removes oxidized guanine, one of the four key nucleobases found in DNA and RNA.

Called GO DNA repair (the GO stands for guanine oxidation), this ability to clear damaged genetic material protects these microbes’ DNA from mutating. While scientists understand how this mechanism works, its origin isn’t well understood.

That’s where the University of Utah’s Horvath Lab and undergraduate Mary Fairbanks come in. She and her team led by biology professor Martin Horvath explored structural biology and biochemistry by examining microbes from the Lost City Hydrothermal Field, an area of marine alkaline hydrothermal vents on the floor of the Atlantic Ocean, a place with little molecular oxygen and even less sunlight.

Like Fairbanks, who gained hands-on experience designing and running experiments, other lab members worked on the project as biology undergraduates. Co-authors include Payton Utzman and Briggs Miller, both 2022 graduates and current graduate student Vincent Mays.

“Working in Dr. Horvath’s lab has taught me how to be curious and be dedicated to a project,” said Fairbanks, who graduated last year and is preparing to enter medical school. “Being able to design my own experiments has given me the opportunity to act as a scientist. I have grown through research and it continues to expand my view of the possibilities of innovation.”

She also contributed to the advancement of science.

Her team discovered the presence of genes associated with GO DNA repair in the metagenome of these microbes, according to their research published May 8 in PLOS ONE, the journal of the Public Library of Science. The finding raises interesting questions. For starters, why have microbes evolved an ability to address the biological harms of oxygen in environments that lack oxygen?

Horvath first learned that a GO repair gene—known as MutY—might be present at the Lost City Hydrothermal Field from a student in his Molecular Biology of DNA lab course, Emily Dart, who graduated in 2016.  Dart had worked with U associate research professor of biology William Brazelton, who collects and studies microbial DNA from Lost City. Analyzing those samples, Dart and her teammates had found genes encoding portions of MutY.

Horvath took the science a step further.

“Since that first analysis,” Horvath wrote in a post describing his research, “the sequence technology improved, more samples from another expedition generated metagenomes with better coverage, and we now have functional tests that show these MutYs from the bottom of the ocean actually work to prevent mutations in lab strains of bacteria.”

Horvath and Brazelton are the senior authors on the published study, which was funded by the National Science Foundation. That its discoveries stem from basic science research by undergraduates, is “something that I am very proud to celebrate!” Horvath wrote.

Before the so-called Great Oxidation Event more than 2 billion years ago, there was no molecular oxygen, or O2, on Earth. The ensuing rise of oxygen in the atmosphere and oceans gave rise to the complex life we know today.

Marine hydrothermal fields like Lost City are similar to the anoxic environments of early Earth, providing an opportunity to study living organisms that may resemble early life forms and possibly offer clues to how life may have appeared on other planets and moons.

Since the Lost City microbes developed repair systems that deal with oxidative stress in an anoxic environment, it’s reasonable to wonder if life on other worlds may have as well, according to Horvath.

His research group also discovered the role that repair genes, including MutY, play in hydrothermal microbes, by associating GO DNA repair with metabolic pathways. These pathways produce oxygen as a byproduct, so MutY may play a part in fixing DNA damage caused by metabolic processes.

Like life itself, learning science also takes many forms beyond the classroom.

“I’ve been encouraged to ask questions and explain findings to form a cohesive pattern that tells a story,” Fairbanks said. The lab experience helped her “see a project from start to finish. I have been able to improve my critical thinking skills and laboratory technique, as well as adapt to change.”

Her team’s research findings show how DNA-based life forms rely on fixing damage caused by oxidation, even in environments without oxygen, and may give scientists a clue as to how life may look on other planets.

“Life finds a way,” intoned Horvath in his post. But the lessons learned by his students may be as much internal as scientific.

As she heads toward a career in the medical field, Mary Fairbanks concluded, “My experience in research will make me a more open-minded thinker.”

• Brian Maffly Science writer, University of Utah Communications
  801-573-2382 brian.maffly@utah.edu