Graduate student Brianna Steiert successfully defended her thesis, entitled "Elucidation of the Chlamydia trachomatis - Host Interactome," on Friday, May 17, 2024. She is shown here with her mentor, Dr. Mary Weber.
Research
Chlamydia trachomatis (C.t.) is the causative agent of the bacterial sexually transmitted infection chlamydia. Chlamydia infections are often asymptomatic and when left untreated can lead to severe consequences like pelvic inflammatory disease, ectopic pregnancy, and sterility. There is also an increased risk of ovarian and cervical cancer in individuals with current or prior infections.
C.t. is an obligate intracellular bacterium meaning it needs a host to survive. Within this host cell, C.t. carves out a niche by generating a walled-off compartment known as the inclusion. To acquire nutrients and protect itself from host defenses, C.t. releases an arsenal of proteins, called effectors, into the host through a needle-like apparatus termed a type III secretion system. The function of most of these effectors remain unknown. My work focused on identifying the host targets of these proteins.
I used affinity purification - mass spectrometry to identify interacting partners for 22 effectors. Using this data set, I demonstrated the C.t. effector CebN binds to Rae1 and nucleoporins, proteins involved in the movement of protein and mRNA into and out of the nucleus. My results indicate that these interactions allow CebN to block proteins, such as STAT1, which normally plays an important role in stimulating production of anti-C.t. factors, thus allowing C.t. to combat the host response.
Additionally, I also demonstrated that the secreted protein CteG binds to the host protein centrin-2 to take control of centrosome duplication, resulting in production of abnormal numbers of centrosomes. Collectively my work highlights the importance of identifying pathways targeted by C.t. to better understand disease progression.
Background
Brianna was born in Springfield, Missouri and is the only child of John and Paula Steiert. Growing up in a household of microbiologists, Brianna’s love of science started early on listening to lectures in utero, filling pipette tip boxes in her dad’s lab, and riding along during field work to help collect samples with her dad’s graduate students during school breaks.
Determined to carve out a niche different from her parents, Brianna majored in Molecular Biology at William Jewell College in Liberty, MO. During this time, she worked in the lab of Dr. Lilah Rahn-Lee, studying cell division mechanisms in Planctomycetes limnophilus. This research sparked her interest in microbiology as a field and proved the apple does not fall far from the tree. While in college, Brianna served as an Editor for the Jewell newspaper and writer for a scientific magazine while studying abroad at Oxford, which kindled an appreciation for effective communication of science to all audiences. She graduated with her BA in 2018. Staying in the Kansas City area, Brianna worked at the University of Kansas Medical Center in the lab of Dr. Bruno Hagenbuch. Here, she researched drug transporters in the liver. Although not microbiology, this work in pharmacology in the academic setting solidified her desire to pursue graduate school.
In 2019, Brianna joined the Microbiology graduate program at the University of Iowa and joined the lab of Dr. Mary Weber in spring 2020. Mary’s lab was the perfect fit as it allowed her to explore her interest in microbiology while expanding her knowledge base in cell/host biology. During her time in the lab, she developed a love for effector protein biology and host-pathogen interactions, characterizing two Chlamydia trachomatis secreted effectors, CteG and CebN. After graduation, Brianna will be joining Dr. Dana Shaw’s lab at the Washington State University in Pullman, WA, as a post-doc. She will continue to study secreted effectors, using ticks as a model for Anaplasma and Borrelia infections.
When she’s not sneaking a kombucha into the lab, Brianna enjoys hanging out with friends, hiking, playing board games, and trying new local brews. She can also be found dragging a friend to the gym or starting a buddy read with friends. When not out and about, she is at home cooking up a new recipe or cuddling with her cat, Sybil.