Engineered Biosensor Proteins for Programming Novel Therapeutic Modalities

Technologies enabling bioengineers to construct cell-based therapies that sense and respond to specific environmental cues may transform our ability to design and implement novel therapeutic strategies that overcome existing barriers to treatment. To date, we lack synthetic biology “parts” that couple exclusively extracellular cues, such as protein mediators of intracellular communication, to engineered circuits comprised of synthetic proteins, RNA, and/or DNA.  To address this need, we are developing a suite of biosensor technologies for transducing extracellular stimuli into defined state changes within the cell.  We have developed the first fully orthogonal cell surface biosensor platform, termed a modular extracellular sensor architecture (MESA), and have described the engineering of a generic dimerization-dependent signal induction mechanism, wherein receptor dimerization results in the release of an engineered transcription factor from the plasma membrane. Here, we present expansion of this technology to integrate both novel biosensor outputs and novel biosensor input modalities. First, we will describe MESA biosensors that reconstitute intracellular enzymatic activities in a dimerization-dependent fashion, providing novel opportunities for performing protein-based logic and coupling MESA output to transcription-independent circuits. We will also describe the development of biosensors that transduce extracellular enzymatic activity into intracellular state changes, which is of relevance for applications such as detection of proteases that typify disease states such as tumor invasion and autoimmune disease (e.g., matrix metalloproteinases). Like many synthetic biology technologies, these biosensor platforms provide powerful tools that may be applied to scientific inquiry and investigation of disease processes as well as novel therapeutic modalities, each of which will be discussed.