Super Resolution Imaging And Tracking Of Protein-Protein Interactions In Sub Diffraction Cellular Space

Imaging localization and dynamics of individual interacting protein pairs is essential but often difficult due to the fluorescent background from other paired and non-paired molecules, particularly in the sub-diffraction cellular space. Here we develop a new method combining Bimolecular Fluorescence Complementation (BiFC) and Photoactivated Localization Microscopy (PALM) for super-resolution imaging and single molecule tracking of specific protein-protein interactions. The method is used to study the interaction of two abundant proteins, MreB and EF-Tu, in Escherichia coli cells. The super-resolution imaging shows interesting distribution and domain sizes of interacting MreB-EF-Tu pairs as a subpopulation of total EF-Tu. The single molecule tracking of MreB, EF-Tu, and MreB-EF-Tu pairs reveals intriguing localization-dependent heterogonous dynamics and provides valuable insights to understanding the roles of MreB-EF-Tu interactions.