Biology subjects

McMahan, J. B.

Publications and source records attributed to McMahan, J. B..

3 recordsLinked to original sources

bioRxiv2024

Fluorescein-Based SynNotch Adaptors for Regulating Gene Expression Responses to Diverse Extracellular Cues

We introduce an adaptor-based strategy for regulating fluorescein-binding synthetic Notch (SynNotch) receptors using ligands based on conjugates of fluorescein isomers and analogs. To develop a versatile system, we evaluated the surface expression and activities of multiple constructs containing distinct extracellular fluorescein-binding domains. Using an optimized receptor, we devised ways to regulate signaling via fluorescein-based chemical transformations, including an approach based on a bio-orthogonal chemical ligation and a spatially controllable strategy via the photo-patterned uncaging of an o-nitrobenzyl-caged fluorescein conjugate. We further demonstrate that fluorescein-conjugated extracellular matrix (ECM)-binding peptides can regulate SynNotch activity depending on the folding state of collagen-based ECM networks. Treatment with these conjugates enabled cells to distinguish between folded versus denatured collagen proteins and enact dose-dependent gene expression responses depending on the nature of the signaling adaptors presented. To demonstrate the utility of these tools, we applied them to control the myogenic conversion of fibroblasts into myocytes with spatial and temporal precision and in response to denatured collagen-I, a biomarker of multiple pathological states. Overall, we introduce an optimized fluorescein-binding SynNotch as a versatile tool for regulating transcriptional responses to extracellular ligands based on the widely used and clinically-approved fluorescein dye.

synthetic biology↗

bioRxiv2023

Controlled protein activities with viral proteases, antiviral peptides, and antiviral drugs

Chemical control of protein activity is a powerful tool for scientific study, synthetic biology, and cell therapy; however, for broad use, effective chemical inducer systems must minimally crosstalk with endogenous processes and exhibit desirable drug delivery properties. Accordingly, the drug-controllable proteolytic activity of hepatitis C cis-protease NS3 and its associated antiviral drugs have been used to regulate protein activity and gene modulation. These tools advantageously exploit non-eukaryotic/prokaryotic proteins and clinically approved inhibitors. Here we expand the toolkit by utilizing catalytically inactive NS3 protease as a high affinity binder to genetically encoded, antiviral peptides. Through our approach, we create NS3-peptide complexes that can be displaced by FDA-approved drugs to modulate transcription, cell signaling, split-protein complementation. With our developed system, we discover a new mechanism to allosterically regulate Cre recombinase. Allosteric Cre regulation with NS3 ligands enables orthogonal recombination tools in eukaryotic cells and functions in divergent organisms to control prokaryotic recombinase activity.

synthetic biology↗

bioRxiv2022

A Genetically Encodable and Chemically Disruptable System for Synthetic Post-Translational Modification Dependent SynNotch Signaling

We describe an engineered "writer/reader" framework for programming post-translational control into synthetic mammalian signaling proteins. In this approach, a bacterially-derived biotin protein ligase (BirA) was used as a "writer" element for the modification of artificial receptors and transcription factors containing a biotin acceptor peptide (AP) fusion tag. To enable modification events to transmit biochemical information, we designed encodable "reader" modules using sequences from a biotinamide-binding antibody. Proteins fused to reader domains were able to interact with AP-tagged polypeptides in a biotinylation-dependent manner, and control over the timing and extent of these interactions could be modulated through both genetic and chemically-based strategies. Genetic and cell-specific control over AP-reader module interactions was achieved via regulated BirA expression, and the interaction states of both intra-and inter-cellular complexes could be modulated with biotinamide-based and bioorthogonally-functionalized compounds. The utility of this approach was demonstrated by installing post-translational and chemogenetic control into synthetic Notch ("SynNotch")-based systems.

biochemistry↗