Imaging the location and dynamics of individual interacting protein pairs is essential but often difficult because of the fluorescent background from other paired and non-paired molecules, particularly in the sub-diffractioncellularspace. Here we develop a new method combining bimolecular fluorescence complementation and photoactivated localization microscopy for super-resolutionimaging and single-molecule tracking of specificprotein-proteininteractions. The method is used to study the interaction of two abundant proteins, MreB and EF-Tu, in Escherichia coli cells. Thesuper-resolutionimaging 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.

Liu Z, Xing D, Su QP, Zhu Y, Zhang JM, Kong XY, Xue BX, Wang S, Sun H, Tao YL, Sun YJ*. (2014) Super-resolution imaging and tracking of protein-protein interactions in sub-diffraction cellular space. Nature Communications, 5:4443.