Cornell University
Peter J. W. Debye Professor
Department of Chemistry and Chemical Biology
April 13th, 2018 – Spring Seminar
Time and Location: Noon in Meyerhoff Chemistry, Room 120
Host: Dr. Minjoung Kyoung
“Single-molecule chemistry: from transcription regulation to living polymerization”
I will present two stories that use single-molecule approaches to interrogate the mechanism and dynamics of biological and chemical processes. In the first story, I will present our work in using super-resolution single-molecule tracking to study transcription regulation in living cells. Binding and unbinding of transcription regulators on chromosome constitute a primary mechanism for gene regulation. While many cellular factors are known to regulate their binding, little is known on how cells can modulate their unbinding for regulation. I will describe that two metal-sensing transcription regulators show unusual concentration and chromosome-conformation dependent unbinding kinetics in bacterial cells, which provide novel mechanisms for facile switching between transcription activation and deactivation in vivo and in coordinating transcription regulation of resistance genes with the cell cycle. In the second story, I will present our work in using magnetic tweezers to track single polymer growth in real time under living polymerization catalysis conditions. I will describe how the real-time growth dynamics of single polymers reveal the formation and unraveling of conformational entanglements that play key roles in the polymerization kinetics and kinetic dispersion among individual polymers.
Key references:
- -Y. Chen, A. G. Santiago, W. Jung, L. Krzeminski, F. Yang, D. J. Martell, J. D. Helmann, P. Chen* “Concentration and chromosome-organization dependent regulator unbinding from DNA for transcription regulation in living cells” Nature Commun. 2015, 6, 7445.
- P. Joshi, D. Panda, D. J. Martell, N. M. Andoy, T.-Y. Chen, A. Gaballa, J. D. Helmann, P. Chen* “Direct substitution and assisted dissociation pathways for turning off transcription by a MerR-family metalloregulator” Proc. Natl. Acad. Sci. USA 2012, 109, 15121-15126.
- Liu, K. Kubo, E. Wang, K.-S. Han, F. Yang, G. Chen, F. A. Escobedo,* G. W. Coates,* P. Chen* “Single polymer growth dynamics” Science 2017, 358, 352-355.