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McKelvey School of Engineering

Brown School

BME Seminar: Taekjip Ha, PhD

Thursday, January 26 | 10:00 AM - 11:00 AM

Uncas A. Whitaker Hall, 218
6760 Forest Park Pkwy, St. Louis, MO 63105, USA

Presenting on “Light, CRISPR and DNA Repair”

Taekjip Ha, PhD, Bloomberg Distinguished Professor of Biophysics and Biophysical Chemistry, Biophysics, and Biomedical Engineering at Johns Hopkins University School of Medicine, will speak on Thursday, January 26, 2023 at 10:00 am CST in Whitaker 218.

Abstract:  CRISPR is a revolutionary technology for genome editing, manipulation and diagnostics. We developed a light-on control for CRISPR, termed very fast (vf) CRISPR that can control Cas9 activity at seconds and micrometer precision. Using vfCRISPR and time-resolved ChIP-seq, we discovered surprisingly rapid detection and repair of Cas9-generated DNA breaks, and ultrafast spreading of damage-induced chromatin modification. Using vfCRISPR and live cell imaging, we found that the first round of repair takes much longer than subsequent rounds and that repair of two alleles in the same cell occur on a similar time scale despite large cell to cell heterogeneity. Using imaging-guided vfCRISPR, we achieved the ultimate resolution of CRISPR control, the single allele resolution.

We also developed a light-off control for CRISPR with unprecedent 99% efficacy. Combining light on and light off controls with multitarget CRISPR, we discovered the extent and time scale of chromatin opening (~1-2 kb and ~30 min, and time scale of chromatin restoration after repair completion. The multitarget CRISPR also allowed us to show that Cas9 is selectively evicted from the PAM-distal side of a break, leading to the loading of a repair factor at the same side.

We used the exquisite sequence specificity of CRISPR with our own superhelicases to create a new genome imaging method called GOLD FISH with a single nucleotide sensitivity, a feat never been achieved for direct hybridization-based imaging.

Registration is required to attend virtually. Please register.

Event Type



McKelvey School of Engineering


Science & Technology, Medicine & Health

Biomedical Engineering


Event Contact

Mimi Hilburg | mhilburg@wustl.edu

Speaker Information

Dr. Taekjip Ha is a Bloomberg Distinguished Professor of Biophysics and Biophysical Chemistry, Biophysics, and Biomedical Engineering at Johns Hopkins University School of Medicine. He is also an investigator with the Howard Hughes Medical Institute. He uses sophisticated physical techniques to manipulate and visualize the movements of single molecules to understand basic biological processes involving DNA and other molecules. His study is focused on pushing the limits of single-molecule detection methods to study protein–nucleic acid and protein-protein complexes and the mechanical basis of their interactions and functions – both in vitro and in vivo – that are important for genome maintenance.

Dr. Ha received his undergraduate degree in Physics, from Seoul National University, Seoul, Republic of Korea in 1990.  He earned his Ph.D. In Physics from the University of Berkeley in 1996. After postdoctoral training at Stanford University, he was a Physics professor at University of Illinois at Urbana-Champaign for fifteen years until 2015.

Dr. Ha serves as a member of Editorial Boards for Science, Cell, eLife, PRX, Structure, PCCP, Physical Biology and Cancer Convergence. He is a member of the National Academy of Science and an elected fellow of the American Academy of Arts and Sciences.

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