Seung-Ryoung Jung †‡, Eunji Kim∥, Wonseok Hwang †‡, Soochul Shin §, Ji-Joon Song *∥, and Sungchul Hohng *†‡§
†Department of Physics and Astronomy, ‡National Center for Creative Research Initiatives, and §Department of Biophysics and Chemical Biology, Seoul National University, Seoul 151-747, Korea
∥ Department of Biological Sciences, KAIST, Daejeon 305-701 Korea
*Correspondence to Ji-Joon Song, Sungchul Hohng
S.-R.J. and E.K. contributed equally to this work.
Argonaute (Ago) is the catalytic core of small RNA-based gene regulation. Despite plenty of mechanistic studies on Ago, the dynamical aspects and the mechanistic determinants of target mRNA binding and dissociation of Ago-guide strand remain unclear. Here, by using single-molecule fluorescence resonance energy transfer (FRET) assays and Thermus thermophilus Ago (TtAgo), we reveal that the 3′-end of the guide strand dynamically anchors at and releases from the PAZ domain of Ago, and that the 3′-end anchoring of the guide strand greatly accelerates the target dissociation by destabilizing the guide-target duplex. Our results indicate that the target binding/dissociation of Ago?guide is executed through the dynamic interplays among Ago, guide, and target.