Sessler Lectureship: Professor Julie Biteen, University of Michigan (Host: W.E. Moerner)
**This seminar is available for in-person attendance.**
"Mapping Biophysical Observations to Biochemical States in Living Microbial Cells"
About the Seminar
Single-molecule microscopy accesses nanometer-scale information with a benchtop microscope, providing a platform to super-resolve fluorescence emission, position, and dynamics, even in living cells. We are building single-molecule methods to address fundamental, unanswered questions in nanotechnology and microbiology. I will introduce the tools that we have developed and then discuss how we applied these experimental methods and data analysis approaches to answer a significant question in cell biology: “How do HP1 proteins recognize and bind methylated histones (H3K9me) to establish transcriptional silencing?” In particular, we investigated the single-molecule dynamics of the HP1 homolog, Swi6, in fission yeast. Using mutants that respectively perturb H3K9me recognition, oligomerization, and nucleic acid binding, we mechanistically defined how each biochemical function associated with Swi6 influences its heterochromatin-specific localization pattern. In sharp contrast with previous in vitro results, we discovered that nucleic acid binding competes with Swi6 chromodomain mediated H3K9me recognition in vivo. These results reveal how HP1 proteins traverse a complex and crowded chromatin landscape on the millisecond timescale and yet recognize H3K9me with high specificity, and the direct, quantitative, and high-resolution approaches have further consequences in understanding subcellular biochemistry and biophysics.
About the Speaker
Julie Biteen is a Professor of Chemistry and of Biophysics at the University of Michigan where her research program develops single-molecule fluorescence and super-resolution microscopy for applications to microbiology and nanomaterials. Dr. Biteen earned an A.B. in Chemistry at Princeton University and a Masters in Applied Physics and a Ph.D. in Chemistry at Caltech. Dr. Biteen trained as a postdoc in the lab of W. E. Moerner at Stanford University, studying structural proteins in living bacteria cells with single-molecule imaging, before joining the University of Michigan faculty in 2010. Based on algorithms for single-molecule localization, tracking, and quantification; investigations of plasmon-coupled fluorescence; and adaptations for cell types including anaerobes and autofluorescent bacteria, the Biteen Lab has achieved fundamental insight of relevance to human health and nanoscience and has developed approaches that can be further applied to other problems in physics, chemistry, and biology. Biteen is a Senior Editor for the Journal of Physical Chemistry and a member of the DOE Biological and Environmental Research Advisory Committee (BERAC). She has been recognized by numerous awards, including the Sessler Distinguished Alumni Lectureship at Stanford (2021), an NSF Award for Special Creativity (2020), the Margaret Oakley Dayhoff Award for Women in Biophysical Sciences (2017), and the Journal of Physical Chemistry Award Lectureship (2016).
Image credit: Michigan Photography