* PHYSICS/BK21 SEMINAR *

Mechanical unfolding of RNA

연사: 현창봉 박사[University of California]

일시: 2007 년 6 월 8 일 13:30

장소: 물리학과 회의실(공학3동 103호)

ABSTRACT:

Mechanical unfoldings of RNA structures, ranging from hairpins to ribozymes, using laser optical tweezer (LOT) experiments have begun to reveal the features of the energy landscape that cannot be easily explored using conventional experiments. Upon application of constant force (f ), RNA hairpins undergo cooperative transitions from folded to unfolded states whereas subdomains of ribozymes unravel one at a time. Here, I study the force dynamics of a simple RNA hairpin using a hree interaction site (TIS) model and Brownian dynamics simulations. In agreement with a LOT experiment, application of constant force or constant loading rate results in bistable cooperative transitions between folded and unfolded states without populating any intermediates. In response to the variations in the force and temperature, RNA hairpins demonstrate extremely rich dynamic behaviors. For the RNA structures with higher complexity from 55-nt TAR-RNA to the 407-nt Tetrhymena thermophila ribozyme, I use a self-organized polymer (SOP) model to predict the kinetic barrier and the force-induced unfolding pathways. The pulling speed dependent unfolding pathways are discussed using the Azoarcus ribozyme. Lastly, I discuss the eect of the handle polymer on the experimental measurement.

문의처: 성우경(054-279-2061, wsung@postech.ac.kr)