Biology subjects

Marzilli, A. M.

Publications and source records attributed to Marzilli, A. M..

3 recordsLinked to original sources

bioRxiv2026

Engineered Allosteric RNA Editors Enable Compact, Stimulus-Responsive Post-Transcriptional Circuits

Translational regulation offers a powerful biological control axis with the potential to enable programmable control over synthetic mRNAs. Here, we introduce inducible Deaminases Acting on RNA (iDARs): deaminase domains (DDs) with conditional RNA-editing activities. Using a domain-insertion strategy, we designed autoinhibited enzymes that can be converted into active RNA editors in response to triggers based on small molecules (chemiDARs), intracellular antigens (antiDARs), protease cleavage (lysiDAR), and optical excitation (optiDAR). Coupling these domains with novel stop codon containing RNA substrates enabled conditional protein translation or transcript degradation. Mutational tuning of inositol hexaphosphate (IP6)-binding pockets produced tightly regulated deaminases with minimal basal activity, facilitating dose-dependent readthrough translation in response to low-nanomolar drug concentration, with dynamic ranges exceeding 100-fold. By encoding iDARs alongside their substrates, we developed "self-editing" polycistronic transcripts capable of directing translation of encoded proteins in a trigger-dependent manner following delivery to cells as in vitro transcribed mRNAs. Overall, iDARs provide a generalizable framework for generating controllable deaminases, enabling the design of post-transcriptional circuits that link biochemical sensing to readouts based on de novo translation or mRNA decay.

synthetic biology↗

bioRxiv2024

RNA-Stabilized Coat Proteins for Sensitive and Simultaneous Imaging of Distinct Single mRNAs in Live Cells

RNA localization and regulation are critical for cellular function, yet many live RNA imaging tools suffer from limited sensitivity due to background emissions from unbound probes. Here, we introduce conditionally stable variants of MS2 and PP7 coat proteins (which we name dMCP and dPCP) designed to decrease background in live-cell RNA imaging. Using a protein engineering approach that combines circular permutation and degron masking, we generated dMCP and dPCP variants that rapidly degrade except when bound to cognate RNA ligands. These enhancements enabled the sensitive visualization of single mRNA molecules undergoing differential regulation within various sub-compartments of live cells. We further demonstrate dual-color imaging with orthogonal MS2 and PP7 motifs, allowing simultaneous low-background visualization of distinct RNA species within the same cell. Overall, this work provides versatile, low-background probes for RNA imaging, which should have broad utility in the imaging and biotechnological utilization of MS2- and PP7-containing RNAs.

bioengineering↗

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↗