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Barry Bruce E404 Walters Life Sciences |
Keywords:
Protein transport, membrane biogenesis, organelle evolution, photosynthesis
Research Area:
Import of proteins into chloroplasts; molecular chaperones
Description of Research:
Eukaryotic cells are defined by their topological complexity. This elaborate compartmentalization enables the metabolic diversity that permits higher order organization into distinct cell and tissue types. However, the membranes that delineate these discreet compartments also present a fundamental barrier for the movement of proteins from their site of synthesis in the cytoplasm. Protein trafficking is the study of the mechanism of how proteins are targeted with high fidelity and efficiency to their ultimate cellular destination. This field involves investigations into protein structure, membrane biophysics, and molecular cell biology.
My laboratory investigates how proteins are targeted and translocated into the plant-specific organelle, the Plastid. This organelle has evolved via endosymbiosis from a free living prokaryotic into one of the most well studied organelles in biology. Although plastids only maintain a minimal genome, the organelle probably performs a complete "prokaryotic" repertoire of metabolic activities. This diverse metabolism has been estimated to require no less that 3000 gene products, most of which have been transferred from the plastid genome into the nuclear genome. These gene products are redirected to their "ancestral" compartment via the acquisition of a transit peptide. The transit peptide is a "new" sequence that has been evolutionarily inserted N-terminal to the coding sequence and has been shown to be both necessary and sufficient to ensure high fidelity transport back into the organelle.
Progress in genomics research has identified thousands of these transit peptides, yet their lack of sequence similarity has suggested an "encoding of information" that has thus far eluded deciphered. How thousands of short sequences (40-80 a.a) can contain common and requisite information, yet reflect no primary similarities suggest that there is some level of secondary or tertiary structure that ensures common activity. My laboratory is attempting to elucidate this unique form of targeting information by a using a combination of approaches including computation analysis, site-directed mutagenesis, structural biology (NMR and CD), and in vitro / in vivo cell biological studies. This work is supported by the NSF Program in Cell Biology.
Selected Publications: