Research

Non-technical description

Traditional biochemistry studies individual molecules under controlled conditions. As our understanding of biology has deepened, however, it has become clear that biological molecules interact in complex systems, where key properties emerge only when the entire system is viewed as a whole. Our lab develops ways to study biomolecules in the context of living cells and tissues. Specifically, we design molecular tools that “report” information about specific biomolecules in vivo.

For instance, biochemical modifications of histone proteins – the scaffolding around which DNA is wrapped within the cell nucleus – can influence the transcription of the surrounding DNA. We have developed fluorescent tags that change color in response to two important and well-studied types of modifications, phosphorylation and methylation, at different residues on histone 3.

We are also working to adapt reporter molecules routinely used in vitro for use in vivo. These reporters are small molecules that cannot be synthesized by the cell's own machinery, but instead must be attached chemically to the biomolecule of interest. Tagging a specific biomolecule with one of these reporters, in the presence of a wide range of other molecules, represents an important challenge. We have re-engineered natural enzymes, such as biotin ligase, transglutaminase, and lipoic acid ligase, to catalyze these tagging reactions quickly and with very high specificity in the live-cell context.

We have applied this new methodology to the study of the AMPA receptor, an ion channel found in the nervous system that is believed to play a key role in learning and memory. By enzymatically tagging the AMPA receptor with fluorescent reporter molecules in vivo, we were able to image the movements of individual receptor molecules on the surface of living neurons. We are applying the same technology to molecules important in nervous system development (neuroligin), cancer (epidermal growth factor receptor), and cholesterol metabolism (LDL receptor).

In summary, by developing new reporters and targeting methods for imaging the biochemical behavior of specific proteins in living cells, we hope to gain an unprecedented view of the complex systems responsible for many biological phenomena.


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