be a place to grow as a scientist and an educator, another role with deep appeal to her? “When I came and interviewed here and met my colleagues, I knew this is where I needed to be,” she recalls. “I realized the integration of research and teaching was what I wanted.” The ensuing 14 years have confirmed the wisdom of Stuart’s decision and made her a paragon of the Marquette teacher-scholar — the only professor to date to be recognized with the university’s top awards for teaching and research, the Marquette Teaching Excellence Award and Lawrence G. Haggerty Faculty Award for Research Excellence. Her pursuit of mitochondrial mysteries is now inseparable from the satisfaction she gets helping students in the classroom grasp sub-cellular interactions — or the camaraderie she feels making advances in her field alongside the undergraduate and graduate students in her lab.
so they can become subunits of the OXPHOS machinery, this investigation remains a fruitful project in Stuart’s lab, funded by a three-year $540,000 grant from the National Science Foundation. A particular focus is the role of a protein known as Oxa1, which anchors ribosomes to the mitochondria’s inner membrane. Stuart helped discover Oxa1 in her German days. Then a few years ago, working as they typically do with yeast as a reliable stand-in for human cells, team members discovered a previously unknown mitochondrial protein. Now known to be present up and down the evolutionary chain from yeast to humans, this hypoxiainduced gene protein, dubbed Hig1, physically joins two of the five complexes in the OXPHOS system and appears to help them coordinate their activity. Through a $340,000 grant from the National Institutes of Health, researchers in Stuart’s lab are working to elucidate this interaction. “We’re trying to understand how Hig1 helps these enzymes hold hands so they can communicate directly. If one has to work hard, it can tell the other one, ‘You need to work hard, too.’ ”
It’s a brilliantly reciprocal system, but one that requires precise tuning. If the OXPHOS machinery underperforms, “it’s as if the body has a power failure,” says Stuart. “The other extreme of over-excitation of these enzymes can also be damaging because they can produce toxic byproducts such as superoxide radicals or reactive oxygen species.” In aiming to better understand this finely honed regulation, Stuart’s team, up until a few years ago, focused primarily on one important mechanism — how much OXPHOS machinery gets built in the first place. Involving the actions of tiny structures within the mitochondria known as ribosomes that synthesize and position necessary proteins
As thrilling as it was to be part of another breakthrough (teams from Utah and Germany also happened upon Hig1 around the same time), the best part of the story for Stuart was something else. An undergraduate assistant in her lab, Andrew Furness, Arts ’07, now a doctoral candidate in evolutionary biology at the University of California–Riverside, made the discovery. “If it wasn’t for a really smart undergraduate working in the lab who said, ‘What’s this?’ we wouldn’t be where we are,” she relates. The story confirms what she appreciates most about her career here. “I got hooked on research and the process of scientific discovery as an undergrad, and that’s why I really loved coming to a place like Marquette. I like research, and I love understanding how a system works and that’s really great, but the most fulfilling part of what I’m doing is using this as a system to educate and train the next generation of scientists.”
Stuart’s lab now shines light on the complex inner workings of mitochondria from more than one direction. To a great degree in vital organs like the heart and a lesser degree in tissue such as fat, cells require ATP to power their workload. And in unlocking energy from it, they convert ATP into a form of cellular spent fuel known as ADP. That’s where a network of five enzymes in the mitochondria kicks in. Through a process called oxidative phosphorylation, this enzyme system — known as the OXPHOS machinery for short — pulls in ADP from the cell and converts its diphosphate into the triphosphate of ATP, fresh fuel to keep the heart pumping.
Dr. Rosemary Stuart Professor, Biological Sciences
“... the most fulfilling part of what I’m doing is using this as a system to educate and train the next generation of scientists.”