Signaling molecules and their activities are well coordinated in space and time to regulate cellular functions in response to mechanical and chemical microenvironment. Based on fluorescent resonance energy transfer (FRET), we have developed genetically encoded biosensors to monitor the dynamic molecular activities (such as Src and FAK activities) in live cells at subcellular compartments when cells interact with their neighbors or mechanical/chemical microenvironment. In a recent study, we show that a ubiquitous signaling protein, Src Homology 2 (SH2) Domain-containing Protein Tyrosine Phosphatase 2 (Shp2), displayed unexpected plasticity of conformational changes via intramolecular interactions within Shp2 (<i>cis</i>-interaction). We found that two phosphorylated regulatory tyrosines upon stimulated phosphorylation can compete for the <i>cis</i>-interaction of the same SH2 domain within Shp2 to achieve plasticity. The antagonistic combination of contextual amino acid sequence and position can create a relatively small difference between the two phosphorylated tyrosines in their overall competitiveness for intramolecular conformational regulation. Enlarging this difference by swapping the sequences at the two tyrosine positions resulted in loss of conformational plasticity and reprogrammed downstream ERK signaling dynamics. We have further engineered a machinery molecule based on Shp2 which allows an integrated capability of imaging and manipulation of single cell life. We suggest that this strategy can serve as a general and basic design principle for natural and synthetic proteins, with their conformations and functions tunable to regulate downstream physiological consequences. As such, molecular engineering and biosensor development can provide powerful tools for the imaging and manipulation of cellular lives at single cell levels.

Molecular engineering for imaging and reprogramming in live cells

251st National Meeting (2016)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.