TagBiFC technique allows long-term single-molecule tracking of protein-protein interactions in living cells

• Published in: Communications biology 2021-03, Vol.4 (1), p.378-378, Article 378
• Main Authors: Shao, Shipeng, Zhang, Hongchen, Zeng, Yong, Li, Yongliang, Sun, Chaoying, Sun, Yujie
• Format: Article
• Language: English
• Subjects: 14/34; 14/35; 14/63; 631/1647/245/2225; 631/80/2373; Biology; Biomedical and Life Sciences; Brightness; Chromatin; Complementation; Dimerization; Life Sciences; Localization; Protein interaction; Proteins; Transcription factors
• ISSN: 2399-3642; 2399-3642
• DOI: 10.1038/s42003-021-01896-7

Protein-protein interactions (PPIs) are critical for cellular activity regulation. Visualization of PPIs using bimolecular fluorescence complementation (BiFC) techniques helps to understand how PPIs implement their functions. However, current BiFC is based on fluorescent proteins and the brightness and photostability are suboptimal for single molecule tracking experiments, resulting in either low spatiotemporal resolution or incapability of tracking for extended time course. Here, we developed the TagBiFC technique based on split HaloTag, a self-labeling tag that could conjugate an organic dye molecule and thus offered better brightness and photostability than fluorescent proteins for PPI visualization inside living cells. Through screening and optimization, we demonstrated that the reconstituted HaloTag exhibited higher localization precision and longer tracking length than previous methods. Using TagBiFC, we reveal that the dynamic interactions of transcription factor dimers with chromatin DNA are distinct and closely related to their dimeric states, indicating a general regulatory mechanism for these kinds of transcription factors. In addition, we also demonstrated the advantageous applications of TagBiFC in single nucleosome imaging, light-burden imaging of single mRNA, low background imaging of cellular structures. We believe these superior properties of our TagBiFC system will have broad applications in the studies of single molecule imaging inside living cells. Shao et al. develop an imaging probe, TagBiFC, to visualize protein-protein interaction in living cells with better signal-to-noise ratio and photostability than fluorescent proteins. This probe provides better localization and longer tracking time and authors visualise transcription factor dimerization, single-molecule nucleosome, and background-free mRNA imaging using TagBiFC.