I have several areas of interest. First, I am interested in the study of protein homeostasis and signaling pathways, with particular interest in development of novel tools for conditionally perturbing and analyzing the function of such pathways in live cells. To this end, I am developing optogenetic tools that allow use of light for precise control of protein function in cells. When combined with optical sensors and other signaling readouts, these can allow real-time perturbing and monitoring of cellular processes. In other work, I am developing sensors that detect perturbations to protein stability, and using these to identify chemical and genetic factors affecting protein homeostasis. These and other projects are described in more detail below.
Light-inducible control of protein activity
Proteins that have inducible activities are useful tools for molecular biology and potentially can be used for therapeutic applications. I am interested in the design and construction of novel protein switches that can be regulated by light, or other protein activities (such as protein binding). These switches can be designed to regulate enzymatic activities, protein interactions, signal transduction pathways, or other activities. The light-activated proteins provide not only fast temporal activation of cellular events, but also spatial and dosage regulation as well.
In recent work in the lab, we developed light-activated modules for protein dimerization based on the Arabidopsis proteins cryptochrome 2 and CIB1, which dimerize upon exposure to blue light. The photo below shows protein translocation induced by light in HEK293 cells, using these dimerization modules. We are currently exploring novel applications of the CRY/CIB system for acute regulation of cellular processes in live cells.
|Before light exposure
||15s post light exposure|
Biosensors for protein misfolding / cytosolic protein homeostasis
I am interested in the development of simple, inexpensive cell-based reporters for protein misfolding that are generalizable, in that they can be used with any protein of interest without prior knowledge of protein function. These reporters are being used to characterize misfolded alleles, to screen for pharmacological chaperones, small molecules that rescue misfolded variants, and to identify genetic pathways affecting cytosolic protein homeostasis.
Characterization of human disease proteins using yeast
The protein alanine : glyoxylate aminotransferase (AGT) is a critical enzyme in both humans and yeast. In humans, deficiency leads to the disease primary hyperoxaluria type I, a severe kidney disease. Many disease-linked mutations have been shown to destabilize AGT, leading to misfolding and subsequent degradation or mislocalization. I am studying stability and mistrafficking of disease variants of alanine:glyoxylate aminotransferase, both in a yeast model and in mammalian cell culture.