Engineered proteins with sensing and activating modules for automated reprogramming of cellular functions

Abstract

Protein-based biosensors or activators have been engineered to visualize molecular signals or manipulate cellular functions. Here we integrate these two functionalities into one protein molecule, an integrated sensing and activating protein (iSNAP). A prototype that can detect tyrosine phosphorylation and immediately activate auto-inhibited Shp2 phosphatase, Shp2-iSNAP, is designed through modular assembly. When Shp2-iSNAP is fused to the SIRP alpha receptor which typically transduces anti-phagocytic signals from the 'don't eat me' CD47 ligand through negative Shp1 signaling, the engineered macrophages not only allow visualization of SIRP alpha phosphorylation upon CD47 engagement but also rewire the CD47-SIRP alpha axis into the positive Shp2 signaling, which enhances phagocytosis of opsonized tumor cells. A second SIRP alpha Syk-iSNAP with redesigned sensor and activator modules can likewise rewire the CD47-SIRP alpha axis to the pro-phagocytic Syk kinase activation. Thus, our approach can be extended to execute a broad range of sensing and automated reprogramming actions for directed therapeutics.