이종봉 교수 토토 승무패, “Loading Dynamics of a Sliding DNA clamp”

DNA복제 단백질인β 토토 승무패가DNA에loading되는 과정을single-moleculeFörsterResonance Energy Transfer (FRET)와single-molecule polarization기술을 이용하여 실시간으로 관측하였다.본 토토 승무패결과는Angewandte Chemie에 게제되었으며(2014년5월22일),이종봉 토토 승무패 실험실의 조원기 박사(제1저자)와김대형학생(공저자)이 실험을 수행하였다.

Sliding DNA 토토 승무패s are loaded at ass/dsDNAjunction by a 토토 승무패 loader that depends on ATP binding for 토토 승무패 opening. Sequential ATP hydrolysis results in closure of the 토토 승무패 so that it completely encircles and diffuses ondsDNA. We followed events during loading of anE. coliβ 토토 승무패 in real time by using single-molecule FRET (smFRET). Three successive FRET states were retained for 0.3 s, 0.7 s, and 9 min: Hydrolysis of the first ATP molecule by theγ토토 승무패 loader resulted in closure of the 토토 승무패 in 0.3 s, and after 0.7 s in the closed conformation, the 토토 승무패 was released to diffuse on thedsDNAfor at least 9 min. An additional single-molecule polarization study revealed that the interfacial domain of the 토토 승무패 rotated in plane by approximately 8° during 토토 승무패 closure. The single-molecule polarization and FRET studies thus revealed the real-time dynamics of the ATP-hydrolysis-dependent 3D conformational change of the β 토토 승무패 during loading at ass/dsDNAjunction.