Optical Sensors and Actuators for Probing Proximity-Dependent Biotinylation in Living Cells

Light-activated BioID - an optically activated proximity labeling system to study protein-protein interactions

Proximity labeling with genetically encoded enzymes is widely used to study protein-protein interactions in cells. However, the accuracy of proximity labeling is limited by a lack of control over the enzymatic labeling process. Here, we present a light-activated proximity labeling technology for mapping protein-protein interactions at the cell membrane with high accuracy and precision. Our technology, called light-activated BioID (LAB), fuses the two halves of the split-TurboID proximity labeling enzyme to the photodimeric proteins CRY2 and CIB1. We demonstrate, in multiple cell lines, that upon illumination with blue light, CRY2 and CIB1 dimerize, reconstitute split-TurboID and initiate biotinylation. Turning off the light leads to the dissociation of CRY2 and CIB1 and halts biotinylation. We benchmark LAB against the widely used TurboID proximity labeling method by measuring the proteome of E-cadherin, an essential cell-cell adhesion protein. We show that LAB can map E-cadherin-binding partners with higher accuracy and significantly fewer false positives than TurboID.

Chemical and Biological Strategies for Profiling Protein-Protein Interactions in Living Cells

Protein-protein interactions (PPIs) play critical roles in almost all cellular signal transduction events. Characterization of PPIs without interfering with the functions of intact cells is very important for basic biology study and drug developments. However, the ability to profile PPIs especially those weak/transient interactions in their native states remains quite challenging. To this end, many endeavors are being made in developing new methods with high efficiency and strong operability. By coupling with advanced fluorescent microscopy and mass spectroscopy techniques, these strategies not only allow us to visualize the subcellular locations and monitor the functions of protein of interest (POI) in real time, but also enable the profiling and identification of potential unknown interacting partners in high-throughput manner, which greatly facilitates the elucidation of molecular mechanisms underlying numerous pathophysiological processes. In this review, we will summarize the typical methods for PPIs identification in living cells and their principles, advantages and limitations will also be discussed in detail.

Proteomic mapping and optogenetic manipulation of membrane contact sites

Membrane contact sites (MCSs) mediate crucial physiological processes in eukaryotic cells, including ion signaling, lipid metabolism, and autophagy. Dysregulation of MCSs is closely related to various diseases, such as type 2 diabetes mellitus (T2DM), neurodegenerative diseases, and cancers. Visualization, proteomic mapping and manipulation of MCSs may help the dissection of the physiology and pathology MCSs. Recent technical advances have enabled better understanding of the dynamics and functions of MCSs. Here we present a summary of currently known functions of MCSs, with a focus on optical approaches to visualize and manipulate MCSs, as well as proteomic mapping within MCSs.