“Observation of Single Membrane Proteins

under Mechanical Tension”

Single-molecule methods, which handle and monitor molecules one at a time, have been a powerful toolkit for elucidating molecular mechanisms underlying many fundamental biological processes. I will talk about two recent efforts made in our lab, where we endeavor to apply single-molecule methods to a special class of proteins, that is, membrane proteins. First, by applying pN-scale force to a single SNARE complex, a main force-generating machine for membrane fusion in all eukaryotes, we reveal large hysteresis in a mechanical unizipping and rezipping cycle of the SNARE complex. With combined application of different single-molecule methods, we show how this rigid SNARE complex is efficiently disassembled by NSF and SNAP. We observed that NSF exploits a spring-loaded mechanism to tightly couple its ATP hydrolysis with unfolding of the SNARE complex. Second, by employing single-molecule fluorescence imaging as the detection scheme, my lab is developing a single-molecule version of the co-immunoprecipitation (co-IP) analysis. Harnessing its single-molecule sensitivity and millisecond time resolution, we quantitatively determine protein-protein interactions and their relevant changes in given cells or tissues. This novel capability will shed light onto the molecular lesions that drive individual cancers at the protein-protein interaction level, where signal transduction physically occurs. I will close the talk with brief outlook for future researches.

20160929_세미나_Prof. Tae-Young Yoon.hwp