(2011) Ph.D. in Department of Chemistry, KAIST
(2005) B.S. in Department of Chemistry, KAIST

(2024~)Associate professor, Department of Chemistry, KAIST
(2019-2024) Assistant professor, Department of Chemistry, KAIST
(2014-2019) Postdoc, The Rockefeller University (PI: Seth Darst)
(2012-2014) Postdoc, The Rockefeller University (PI: Rod MacKinnon)
(2011-2012) Postdoc, KAIST (PI: Jie-Oh Lee)

We utilize cryo-electron microscopy (cryo-EM) to understand how biomolecules work. Recent advances in cryo-EM, thanks to the improvement of a direct electron detector and data analysis software, have revolutionized the structural biochemistry field over the last several years. As a result, we started to see atomic structures of diverse biomacromolecules in more cell-like environments. Many biological processes await to reveal themselves with this amazing methodology.

Multi-subunit RNA polymerase (RNAP) is a key enzyme sustaining life. RNAPs are highly conserved from E.coli to human and provide room for other proteins/nucleic acids to interact for elaborate gene regulation. Recent advances of cryo-EM open the door to the structural study of RNAPs. We are looking at structures of RNAPs in different contexts of life.

The human microbiome affects humans either indirectly by producing various metabolites or directly through contact with host cells. The significance of the microbiome in multiple contexts of human life has been studied, but the chemical basis of how microbiota interact with the host through microbiome-derived metabolites just started to reveal. We are look at microbiome-derived secondary metabolites' biosynthetic enzymes.

The Molecular Biophysics Laboratory at KAIST, led by Professor Jin Young Kang, explores the molecular mechanisms of transcription regulation and natural product biosynthesis by integrating structural biology (cryo-EM, X-ray crystallography) and biochemical approaches.

- Structural Mechanisms of Bacterial Transcription Regulation

To understand how RNA elements regulate transcription, we resolved the cryo-EM structure of bacterial RNA polymerase in complex with an RNA regulatory element, HK022 put (Hwang, Nat. Comm., 2022). This study revealed how a nascent RNA modulates transcriptional pausing. We continues to investigate RNA polymerase regulation at the structural level.

- Molecular Architecture of Natural Product Biosynthesis

Colibactin is a genotoxic compound produced by the human microbiome that promotes colorectal cancer. We determined cryo-EM structures of colibactin biosynthetic enzymes, ClbC and ClbI, providing mechanistic insight into their catalytic functions (Kim, Kim, Lee, Structure, 2025). Ongoing work aims to expand this approach to other microbial biosynthetic systems to uncover general principles of enzyme-mediated chemical assembly.

- Development of a Time-Resolved Cryo-EM Platform

In collaboration with Prof. Wonhee Lee’s lab (Dept. of Physics, KAIST), we developed a time-resolved cryo-EM system using a parylene-based microfluidic system (Hwang, Adv. Funct. Mater., 2025). This platform enables real-time capture of transient biochemical intermediates and offers new opportunities to study dynamic molecular processes.