title: Highly photostable, reversibly photoswitchable fluorescent protein with high contrast ratio for live-cell superresolution microscopy.
abstract: Two long-standing problems for superresolution (SR) fluorescence microscopy are high illumination intensity and long acquisition time, which significantly hamper its application for live-cell imaging. Reversibly photoswitchable fluorescent proteins (RSFPs) have made it possible to dramatically lower the illumination intensities in saturated depletion-based SR techniques, such as saturated depletion nonlinear structured illumination microscopy (NL-SIM) and reversible saturable optical fluorescence transition microscopy. The characteristics of RSFPs most critical for SR live-cell imaging include, first, the integrated fluorescence signal across each switching cycle, which depends upon the absorption cross-section, effective quantum yield, and characteristic switching time from the fluorescent "on" to "off" state; second, the fluorescence contrast ratio of on/off states; and third, the photostability under excitation and depletion. Up to now, the RSFPs of the Dronpa and rsEGFP (reversibly switchable EGFP) families have been exploited for SR imaging. However, their limited number of switching cycles, relatively low fluorescence signal, and poor contrast ratio under physiological conditions ultimately restrict their utility in time-lapse live-cell imaging and their ability to reach the desired resolution at a reasonable signal-to-noise ratio. Here, we present a truly monomeric RSFP, Skylan-NS, whose properties are optimized for the recently developed patterned activation NL-SIM, which enables low-intensity (∼100 W/cm(2)) live-cell SR imaging at ∼60-nm resolution at subsecond acquisition times for tens of time points over broad field of view.
authors: Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China; Institute of Entomology, School of Life Sciences, Central China Normal University, Wuhan, 430079, Hubei, China;
authors: Xi
authors: X
authors: Zhang
authors: Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China; Beijing Key Laboratory of Noncoding RNA, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China;
authors: Mingshu
authors: M
authors: Zhang
authors: Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147; National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China;
authors: Dong
authors: D
authors: Li
authors: Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China;
authors: Wenting
authors: W
authors: He
authors: Institute of Entomology, School of Life Sciences, Central China Normal University, Wuhan, 430079, Hubei, China;
authors: Jianxin
authors: J
authors: Peng
authors: Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147; betzige@janelia.hhmi.org pyxu@ibp.ac.cn.
authors: Eric
authors: E
authors: Betzig
authors: Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China; Beijing Key Laboratory of Noncoding RNA, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China betzige@janelia.hhmi.org pyxu@ibp.ac.cn.
authors: Pingyong
authors: P
authors: Xu
mesh_terms: D058948:Cell Tracking / Q000379:methods*; D049452:Green Fluorescent Proteins / Q000737:chemistry*; D008027:Light; D008164:Luminescent Proteins / Q000737:chemistry*; D008856:Microscopy, Fluorescence / Q000379:methods*; D059629:Signal-To-Noise Ratio
chemical_list: D008164:Luminescent Proteins; D049452:Green Fluorescent Proteins
keywords: Skylan-NS; fluorescent protein; live-cell imaging; microscopy; superresolution