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Principal Investigator: Kimberly Elizabeth Beatty
Organization: OREGON HEALTH & SCIENCE UNIVERSITY
Fiscal Year: 2024
Award: $385,000
Funding agency: National Institute of General Medical Sciences
Abstract
The Beatty group's research program is investigating how cellular proteins organize and interact in space
and time. We use the principles of chemical biology to create new technologies for labeling and imaging
proteins with an innovative set of reporters.
Recent advances in imaging instrumentation and computational analysis have created new opportunities
for examining the molecular basis of disease with exceptional detail. Researchers can now interrogate
features ranging in size from single molecules (e.g., drugs or proteins) to whole organisms, uncovering how
proteins organize to create living systems. The central obstacle that has limited progress in such studies is the
shortage of methods for labeling proteins for fluorescence microscopy (FM), electron microscopy (EM), or
correlative light and EM (CLEM). As a result, multi-color imaging studies most often rely on immunolabeling—
a method with many drawbacks. Imaging across size dimensions, termed “multiscale microscopy”, would
benefit from new genetic tags for labeling proteins with bright organic fluorophores (for FM), electron-dense
nanoparticles (for EM), or other chemical reporters. Ideal tags would be small, specific, and biocompatible.
The Beatty group has successfully tackled this challenge. In the last 5 years, our team created new
genetic tags named versatile interacting peptide (VIP) tags. VIP tags have the high affinity and specificity of an
antibody, but are an order of magnitude smaller in size. A small tag (4.3-6.2 kDa) reduces the impact on
protein structure or function, particularly when compared to 27 kDa fluorescent proteins (e.g., GFP). VIP tags
enable the effortless switching from conventional FM to high-resolution imaging, including EM, without
changing the genetic tag.
We now propose to build upon this concept and further develop this technology. With the support of
NIGMS, we will expand the set of VIP tags to enable the imaging of multiple proteins at the same time. We will
add a new class of genetic tags that use novel dimerization motifs to facilitate multi-color, multiscale
microscopy. We will use new tags in optimized, user-friendly workflows for imaging receptors across size
scales and platforms, including FM, EM, and CLEM (i.e., multiscale microscopy). Throughout our work, new
tags and methods will be validated through in-depth studies of two receptors that control iron uptake:
transferrin receptor 1 (TfR1) and transferrin receptor 2 (TfR2). We will make new discoveries on TfR2's
function, binding interactions, and trafficking by labeling receptors with environmental sensors, catalysts (e.g.,
for proximity-based labeling), nanoparticles, and other small molecule reporters.
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