Strength in Numbers: USU Undergrad Biochemistry Researcher Studies Bacterial Processes

Utah State University undergraduate Tristen Teeples admits spending his rare moments of free time immersed in science-infused tomes is “a bit nerdy.” His current read is author Philipp Dettmer’s New York Times bestseller Immune: A Journey Into the Mysterious System That Keeps You Alive.

“But I love reading it, and other books like it, almost as much as I love school,” says the Honors student and biochemistry major, who has been working in faculty mentor Nick Dickenson's lab for nearly a year.

With Dickenson, Teeples studies a gram-negative genus of bacteria, known as Shigella, which causes a nasty gut bug in humans called shigellosis. Though generally not fatal in developed countries, the contagious, diarrhea-causing illness is responsible for approximately 269 million worldwide infections and more than 200,000 deaths annually.

In poverty-stricken communities short on water and adequate sanitation, outbreaks can be hard-hitting, especially among children and the elderly. Additionally, while most people recover on their own without antibiotics, certain strains of the bacteria cause more serious illness and are increasingly antibiotic-resistant.

Hence the search for a vaccine.

“I’m specifically studying invasion plasmid antigen D, known as ‘IpaD,’ a key protein in the Shigella Type Three secretion system,” says Teeples, who grew up in Logan, Utah. “We isolated a new oligomeric version of this recombinant protein in Dr. Dickenson’s lab.”

“Oligomeric” refers to a protein composed of more than one polypeptide chain. What the first-generation college student and his fellow lab members are learning about this protein could advance efforts to better understand its role in pathogenesis and in development of an effective vaccine against shigellosis.

Teeples will present his efforts in characterizing IpaD on Tuesday, April 9, during the first day of USU Research Week 2024’s Student Research Symposium. He will display a research poster during the 10:30-11:20 a.m. session in the Main Atrium of the Merrill-Cazier Library.

Teeples says the rod-shaped Shigella flexneri bacterium uses its Type Three secretion apparatus, with IpaD at its tip, to inject protein effectors into human cells. These effectors then support cellular invasion and defense against the host immune system.

“Using several biochemical techniques, we can observe critical information about IpaD’s oligomeric structure, featuring multiple copies of the protein that regulate the timing of this delicate process and prevent the bacterium from injecting protein too soon and missing the target,” he says. “These characteristics make understanding this protein crucial for determining how to develop a vaccine.”

Dickenson says previous research has shown IpaD resides at the tip of the Type Three secretion apparatus “needle” as an oligomer — specifically a pentamer — and this configuration is required for proper function.

“But Tristen has isolated an IpaD oligomer in solution, independent from the apparatus needle itself, and this provides us opportunities to assess the properties of the oligomeric IpaD complex and understand how it may function at the tip of the needle,” he says.

Teeples realized his love of chemistry and biochemistry during his studies at Logan High School.

He praises a “great chemistry teacher,” who, unbeknownst to him as he pursed a research slot with Dickenson, was Dickenson’s wife.

“I really didn’t make the connection until I started working in Dr. Dickenson’s lab,” Teeples says.

With no research experience, Teeples learned lab procedures, techniques and skills from the ground up.

“I admire Tristen’s enthusiasm and determination, along with his courage and persistence in seeking a place in my lab,” says Dickenson, associate professor in USU’s Department of Chemistry and Biochemistry. “He doesn’t give up, and that’s an important lesson for other undergrads. It takes just that crucial bit of courage to approach a faculty member, state why you want to work in a particular lab and your willingness to learn. And Tristen did this very early in his USU career, before he’d completed much coursework in his major.”