Chemical Tools for Molecular Imaging of Proteins and Pathogens

Tracking Mycobacterial Hydrolases with Enzyme Activated Probes

Mycobacterium tuberculosis (Mtb) is the etiologic agent of tuberculosis (TB), which infects one-third of the human population and kills 1.5 million people every year.  Global efforts to eradicate TB face a variety of obstacles, including the lack of an inexpensive rapid diagnostic test for TB and the estimated 2 billion asymptomatic people infected with latent TB. 

The Beatty Group is using chemical tools and novel assays to detect enzymes (e.g., sulfatases and esterases) associated with latent and active TB.  Much of our effort is focused on creating new fluorogenic probes that are activated by Mtb-associated enzymes to produce a bright fluorescent signal.  In prior work, we ascertained that fluorogenic probes can be used in native protein gel assays for rapid pathogen profiling (PNAS 2014, ChemBioChem 2015).  Now we are synthesizing an expanded series of probes in order to identify molecules with improved specificity for Mtb.  We anticipate that these “next generation” probes will be ideal for quantifying bacterial burden in patient samples. 

Additionally, the native protein gel-based assays optimized by our group are an ideal platform for classifying Mtb metabolic states (latent vs. active) and for examining reactivation from a dormant state.  Through our research, we will discover new Mtb biomarkers for tracking infections in living systems and creating novel diagnostic assays. 

The long term goal of our research is to develop simple point-of-care diagnostic assays for TB.  These assays would help to identify the 3 million missed TB cases a year and bring humanity one step closer to TB eradication.



Genetically Encoded Protein Tags for Multi-Target Imaging

     Cellular proteins rarely act in isolation, but instead engage with various macromolecules and sub-cellular structures to control normal and disease-associated cellular processes.  High resolution microscopy can be used to examine cellular proteins and nanostructures, but such studies are limited by the lack of chemical tools for tracking multiple proteins.

     The Beatty Group seeks to remove this obstacle by creating a suite of innovative protein tags that can be used to image multi-component protein complexes relevant to human health.  Our protein tags are based on a heterodimeric coiled-coil interaction, which is small, specific, and biocompatible.  They are designed to be versatile, particularly for switching between fluorescence and EM imaging platforms.  Moreover, careful selection of heterodimeric pairs will enable us to track multiple proteins simultaneously.

     We anticipate that these new protein tags will be useful in a wide variety of applications.  We are working closely with collaborators at OHSU and other universities to apply our technology towards different targets, including cancer signaling networks and the iron processing machinery.