Danielle McFee, a PhD student in Biology, is studying how respiratory oxidases allow Acinetobacter baumannii, colloquially known as the “Iraq bacterium,” to thrive in the gut and infect other organ systems. This important work is critical as A. baumannii is typically found in hospital settings where patients are at their most vulnerable for infection, and the bacteria have become increasingly antibiotic resistant. The pathogen may have originated in soil and was carried back to the U.S. by soldiers who returned from deployment in the middle east. A. baumannii was particularly challenging during the COVID-19 pandemic, causing secondary bacterial infections and ventilator-associated pneumonia.
Danielle completed her Bachelor’s in Biochemistry at Sienna College where she participated in laboratory research for more than two years. Lab life became a passion for her as she took on every role from lab assistant to chemical safety officer. Danielle studied how the change in cytosolic and vacuolar pH that occur as Saccharomyces cerevisiae age impacted the frequency of mobile genetic element replication, or retrotransposition, in the yeast’s genome. She created overexpression strains of the Pma1 proton pump and Vacuolar ATPase to mimic the pH of older mother cells, discovering overexpression of these proteins increased the rate of retrotransposition. Similarly, for a strain with decreased Pma1 expression to mimic younger daughter cells, lower rates of retrotransposition were observed. Overall, Danielle helped identify that controlling retrotransposition rates in yeast may depend on age-associated cytosolic pH regulation.
Danielle, who grew up in the Capital District, was familiar with RPI and its reputation for impactful research. Interested in virology, pathogens, treatment responses, and interdisciplinary projects, she joined Rensselaer’s Biology department in 2022. Intending to join Dr. Barquera’s lab, she found rotating through the other labs during the matchmaking process a great experience as she learned new techniques and developed relationships with multiple faculty and graduate students. Dr. Barquera shares that Danielle is an “exceptional graduate student,” stating, “I couldn’t ask for a better student; she is intelligent, hardworking, and proactive.” She has co-authored a published paper and is currently working on two first author papers. Danielle explains, “One of the most exciting aspects of my work has been identifying one of these oxidases as a cyanide-insensitive oxidase (CIO), which may assist A. baumannii in infecting the liver. The CIO might also play a crucial role in co-infections with cyanide-producing bacteria, such as Pseudomonas aeruginosa, in diseases like cystic fibrosis.” The work has potential to inform treatment strategies and future antibiotic development because two of the oxidases, including CIO, have no human homologues. Discovery of a low-potential quinone previously not described in A. baumannii has implications for the electron transport chain that could lead to a better understand of how A. baumannii survives in and infects low oxygen tissues of our bodies. Overall, understanding the biochemical mechanisms that allow A. baumannii to infect and colonize the human body will lead to better informed treatment of infection and antibiotic development.
Post graduation, Danielle looks forward to continuing research in biochemistry and microbiology, particularly in antibiotic development and testing to address the growing problem of antibiotic resistance.
An avid music fan, Danielle played the flute and piccolo through high school and college, thoroughly enjoying traveling to sports events as a member of the College Pep Band. She often attends concerts of all kinds, most recently the Philadelphia Orchestra, Glass Animals, and Guardin. Her current obsession is Kpop music, usually pumped into her headphones in the lab.
