Kountz tracks methyls in microbe metabolism
Duncan Kountz became interested in microbial biochemistry through a seemingly standard source: a textbook. But this wasn't a textbook assigned for class or research — he chose it himself because it seemed interesting, a habit he started in high school.
"Textbooks help me expand what I'm exposed to," Kountz said, "and I find them perfectly tolerable as long as they're on a subject I'm interested in."
The habit helped him prepare for a career in science, which he knew he wanted to pursue from the time he was in high school. Following a family legacy, he attended Ohio State University and sought research opportunities. He started out in a developmental biology lab, but that textbook, "The Physiology and Biochemistry of Prokaryotes," inspired a move to microbial metabolism. He contacted , an OSU researcher in the field, and joined Krzycki's lab as a sophomore.
"Complexity and diversity really interest me, and I found that in microbial physiology, those are both on display," Kountz said. "Microbes may seem like they're a simple system, but they're also amenable to detailed work."
The Krzycki lab was finishing a project on an enzyme belonging to a superfamily of methyltransferases, and Kountz wanted to investigate similar enzymes in the context of the gut microbiome. He observed that a particular gut bacterium, Eubacterium limosum, encoded many of these enzymes and could utilize several unusual molecules for its growth. He focused on one in particular, carnitine, and tracked down the enzymes responsible for its metabolism.
His research shows how microbial metabolism can affect both microbial prosperity and the health of the human host, as carnitine metabolism can produce toxic byproducts. Kountz was excited about the findings, in part for this potential real-world applicability.
"I think we are really at the dawn of using microbes to solve problems," he said. "I'm excited about the idea of engineering or finding new microbes with interesting properties that we can exploit to make human life better."
Now a fourth-year Ph.D. student in at Harvard, Kountz said his textbook count currently exceeds 100.
Methyl-removing enzyme diverts toxin precursor
Gut bacteria can produce harmful compounds as a byproduct of their normal metabolism. Carnitine, a quaternary amine found abundantly in red meat, can lead to production of a toxin precursor called trimethylamine, or TMA, during digestion. TMA is converted in the liver to TMA oxide, a marker of cardiovascular disease.
Duncan Kountz and colleagues at Ohio State showed that the gut bacteria Eubacterium limosum can use carnitine as fuel, thereby potentially curbing TMA production. They also identified a new metabolite, called norcarnitine, produced by demethylation of carnitine.
Seeking to identify the enzymes involved in this metabolic transformation, Kountz noticed that E. limosum encoded many enzymes in the MttB superfamily. MttB proteins are involved in methyl transfer reactions.
Kountz characterized the enzymes involved in this pathway and identified a methyltransferase, MtcB, that demethylates carnitine and shuttles the product into pathways responsible for energy utilization and biogenesis.
The highlights how metabolic activities in gut microbia may promote health by preventing production of toxin precursors.
Enjoy reading ASBMB Today?
Become a member to receive the print edition four times a year and the digital edition monthly.
Learn moreGet the latest from ASBMB Today
Enter your email address, and we鈥檒l send you a weekly email with recent articles, interviews and more.
Latest in People
People highlights or most popular articles
Meet the 2025 SOC grant awardees
Five science outreach and communication projects received up to $1,000 from ASBMB to promote the understanding of molecular life science.
Unraveling cancer鈥檚 spaghetti proteins
MOSAIC scholar Katie Dunleavy investigates how Aurora kinase A shields oncogene c-MYC from degradation, using cutting-edge techniques to uncover new strategies targeting 鈥渦ndruggable鈥� molecules.
How HCMV hijacks host cells 鈥� and beyond
Ileana Cristea, an ASBMB Breakthroughs webinar speaker, presented her research on how viruses reprogram cell structure and metabolism to enhance infection and how these mechanisms might link viral infections to cancer and other diseases.
Understanding the lipid link to gene expression in the nucleus
Ray Blind, an ASBMB Breakthroughs speaker, presented his research on how lipids and sugars in the cell nucleus are involved in signaling and gene expression and how these pathways could be targeted to identify therapeutics for diseases like cancer.
In memoriam: William S. Sly
He served on the 麻豆传媒色情片 and 麻豆传媒色情片 Biology Council in 2005 and 2006 and was an ASBMB member for 35 years.
ASBMB committees welcome new members
Members joined these committees: Education and Professional Development, Maximizing Access, Meetings, 麻豆传媒色情片, Public Affairs Advisory, Science Outreach and Communication, Student Chapters and Women in Biochemistry and 麻豆传媒色情片 Biology.