Brianna Bibel
Assistant Professor of Chemistry and Biochemistry Loyola Marymount University
Biography
Bri received a B.S. in Biology from Saint Mary’s College of California (SMC), followed by a PhD from Cold Spring Harbor Laboratory (CSHL)’s Graduate School of Biological Sciences in Cold Spring Harbor, New York. There, in the lab of Dr. Leemor Joshua-Tor, she used a combination of biochemical, biophysical, and structural methods to gain a better understanding of how gene expression is regulated through the RNA interference (RNAi) pathway, focusing on the Ago2 protein. After graduating in October, 2021, she then carried out postdoctoral research exploring the effects of antibacterial antibiotics on mitochondrial translation in Dr. Danica Fujimori’s lab at the University of California, San Francisco (UCSF), using biochemical (e.g. mitochondrial ribosome profiling/sequencing) and structural techniques. Before joining the faculty at LMU in 2025, she taught Biochemistry and Chemistry and mentored undergraduate researchers as a Visiting Professor at SMC.
She finds biochemistry fascinating and has a great passion for sharing its wonders freely with whoever will listen. She maintains a biochemistry blog, “The Bumbling Biochemist,” with associated content on Facebook, Instagram and YouTube. Through these channels, she explains both core biochemical concepts and laboratory techniques in detail but using accessible language and infographics. She is deeply involved in the undergraduate education community and is a Cohort Fellow of the Malate Dehydrogenase CUREs Community, leading students in Course-based Undergraduate Research Experiences expressing, purifying, and experimenting with MDH.
Education
Saint Mary's College of California
Bachelor of Science
Biology
2016
Cold Spring Harbor Laboratory School Graduate School of Biological Sciences
Ph.D.
Biological Sciences
2016
Social
Areas of Expertise
Affiliations
- American Society for Biochemistry and Molecular Biology (ASBMB)
- American Chemical Society (ACS)
- Malate Dehydrogenase CUREs Community
- American Society for Mass Spectrometry (ASMS)
- International Union of Biochemistry and Molecular Biology (IUBMB)
- Green Chemistry Teaching and Learning Community (GCTLC)
Courses
Articles
Context-specific inhibition of mitochondrial ribosomes by phenicol and oxazolidinone antibiotics
Nucleic Acids ResearchBrianna Bibel; Tushar Raskar; Mary Couvillion; Muhoon Lee; Jordan I Kleinman; Nono Takeuchi-Tomita; L Stirling Churchman; James S Fraser; Danica Galonić Fujimori
2025-02-10
The antibiotics chloramphenicol (CHL) and oxazolidinones, including linezolid (LZD), are known to inhibit mitochondrial translation. This can result in serious, potentially deadly, side effects when used therapeutically. Although the mechanism by which CHL and LZD inhibit bacterial ribosomes has been elucidated in detail, their mechanism of action against mitochondrial ribosomes has yet to be explored. CHL and oxazolidinones bind to the ribosomal peptidyl transfer center (PTC) of the bacterial ribosome and prevent incorporation of incoming amino acids under specific sequence contexts, causing ribosomes to stall only at certain sequences. Through mitoribosome profiling, we show that inhibition of mitochondrial ribosomes is similarly context-specific—CHL and LZD lead to mitoribosome stalling primarily when there is an alanine, serine, or threonine in the penultimate position of the nascent peptide chain. We further validate context-specific stalling through in vitro translation assays. A high-resolution cryo-electron microscopy structure of LZD bound to the PTC of the human mitoribosome shows extensive similarity to the mode of bacterial inhibition and also suggests potential avenues for altering selectivity. Our findings could help inform the rational development of future, less mitotoxic, antibiotics, which are critically needed in the current era of increasing antimicrobial resistance.
Glycolysis Can Be Fun: Rediscovering Glycolysis as a Problem-Solving Introduction to Metabolism
CourseSourceLauren A. Genova; Kristen Procko; Catherine L. Grimes; Caroline Williams; Kathleen Cornely; Audrey Shor; Amy Styer Greene; Brianna Bibel; Sanjana V. Kumar; Harold B. White
2024-08-19
A thorough understanding of glycolysis forms a foundation for students to analyze subsequent topics in metabolism, a core competency recognized by multiple national societies for biology and biochemistry. However, when confronted with the names of over ten chemicals and enzymes, along with various energy inputs and outputs, students can regard glycolysis as a daunting memorization task. Here we describe a card sorting activity in which small groups of students work out the steps of the glycolysis pathway before any lectures on the topic. They examine the chemical structures of glycolytic intermediates and deduce their logical order. Subsequent analysis of the reactions and the role of cofactors and substrates is reinforced with a POGIL®-inspired worksheet. In the process, the students engage in productive discussions of topics often introduced didactically in lecture. The activity was implemented at six different institutions in small (~12 students) and large classrooms (100+ students), and can be adapted to hybrid/online formats. This highly engaging exercise has been well-received by students and instructors in various undergraduate course contexts.
Target binding triggers hierarchical phosphorylation of human Argonaute-2 to promote target release
eLifeBrianna Bibel; Elad Elkayam; Steve Silletti; Elizabeth A Komives; Leemor Joshua-Tor
2022-05-31
Argonaute (Ago) proteins play a central role in post-transcriptional gene regulation through RNA interference (RNAi). Agos bind small RNAs (sRNAs) including small interfering RNAs (siRNAs) and microRNAs (miRNAs) to form the functional core of the RNA-induced silencing complex (RISC). The sRNA is used as a guide to target mRNAs containing either partially or fully complementary sequences, ultimately leading to downregulation of the corresponding proteins. It was previously shown that the kinase CK1α phosphorylates a cluster of residues in the eukaryotic insertion (EI) of Ago, leading to the alleviation of miRNA-mediated repression through an undetermined mechanism. We show that binding of miRNA-loaded human Ago2 to target RNA with complementarity to the seed and 3’ supplementary regions of the miRNA primes the EI for hierarchical phosphorylation by CK1α. The added negative charges electrostatically promote target release, freeing Ago to seek out additional targets once it is dephosphorylated. The high conservation of potential phosphosites in the EI suggests that such a regulatory strategy may be a shared mechanism for regulating miRNA-mediated repression.
