Biophysical Society Bulletin | February 2023

Biophysicist in Profile

Taekjip Ha Area of Research Single molecule studies of genome maintenance

Institution Johns Hopkins University

At-a-Glance

Taekjip Ha , Professor of Biophysics and Biomedical Engineering at Johns Hopkins University, is the Biophysical Society’s incoming president. His lab uses single-molecule imaging and manipulation techniques to study protein functions and chromatin dynamics and uses the knowledge gained to engineer new protein behaviors and functions. To young biophysicists, he offers this advice: “There is so much to learn and so little time, so optimize your trajectory to maximize learning.”

Taekjip Ha

Taekjip “TJ” Ha , incoming Biophysical Society president, grew up in Seoul, South Korea. His parents worked in early child hood education, in classroom teaching and administration. As a young person, he was fascinated with early 20th century physicists and wanted to become a theoretical physicist. He studied physics as an undergraduate at Seoul National University, and then traveled to the United States to pursue his PhD in physics at the University of California, Berkeley with advisers Shimon Weiss and Daniel Chemla . “It was only after joining a physics PhD program that I realized that there was experimental physics that had enough theory—at least for me,” Ha shares. “My interest shifted from semiconductor physics to chemical physics and eventually to biophysics, largely through a series of accidental meetings with scientists and their work.” During his PhD study, Ha built a near-field scanning optical microscope that enabled high time and spatial resolution. Weiss saw the potential for the techniques Ha was develop ing to be used in single-molecule research and encouraged him. The two regularly had long discussions, pitching and poking holes in ideas for research directions. After completing his PhD, Ha worked as a postdoctoral fel low—first for a year in Weiss and Chemla’s lab at Lawrence Berkeley National Laboratory and then for two and a half years with Steven Chu at Stanford University. In both labs, he worked on single-molecule fluorescence studies of biomole cules. “As a postdoc, I was looking for a biological system to study using single-molecule FRET when I read a review paper on helicases and kinesin written by Tim Lohman and Ron Vale ,” Ha says. “I contacted Tim to start our helicase collaboration and that led me to my current and long-running interest in proteins that function in the maintenance of our genome integrity.”

Following his second postdoctoral position, in August 2000 he was hired as an assistant professor in the Department of Physics and Center for Biophysics and Computational Biology at the University of Illinois at Urbana-Champaign (UIUC). He remained there until 2015, during which time he became a full professor and served as co-director of the Center for Physics of Living Cells (2008–2015) and director of the Center for Biophysics and Quantitative Biology (2013–2014). Zaida “Zan” Luthey-Schulten met Ha when his family moved into the house across from her home in Urbana, Illinois. “Later in the Physics Department at the UIUC, he and my husband, Klaus Schulten , were the first director (Ha) and co-director (Schulten) of our NSF Physics Frontier Center in Biological Physics: Center for the Physics of Living Cells (CPLC),” Lu they-Schulten recalls. “Part of the success of CPLC was the emphasis on joint experimental and theoretical/computa tional biological physics starting with the directors and in our summer school and center projects.” Luthey-Schulten and Ha began a collaboration, publishing together for the first time in Nature in 2014. “Then again in 2021 ( Nature Communications ) and 2020 ( Frontiers in Molec ular Biosciences ) on stochastic simulations and experimen tal measurements using super-resolution single-molecule imaging of small RNA (SgrS) interacting/regulating mRNA of ptsG, the main sugar transporter in bacteria. More recently, we are working on imaging and analyzing cell division in the living minimal cell JCVI-syn3A and comparisons to some of its precursors. Taekjip’s lab has also measured the location of key proteins in the minimal cell involved in sugar transport and cell division,” she explains. “As I have been focusing the ef forts of my lab to build a complete 4DWCM of the minimal cell over the complete cell cycle, this is extremely exciting work for me. Taekjip’s lab is so talented and work on major prob lems in nuclear dynamics of eukaryotic cells—a new direction where hopefully Taekjip and I will have equally successful collaborations in the future.”

February 2023

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