DANNY SCHNELL'S LAB

The long-term goal of our research is to understand the mechanism of protein import into plant chloroplasts as a model for protein targeting and organelle biogenesis in plant/eukaryotic cells. We have identified a set of chloroplast membrane proteins, the Toc and Tic proteins, which recognize and transport nuclear-encoded preproteins into chloroplasts. We are using biochemical, cell biological and genetic techniques to define the activities of individual Toc/Tic components with the aim of understanding how these complexes selectively recognize chloroplast proteins and transport them across the double-membrane of the chloroplast envelope. Of particular interest is the role of two membrane-associated GTP-binding proteins, Toc34 and Toc159, in regulating the recognition of preproteins and the initiation of their transport across the membrane. A second major goal of our studies is to understand the role of protein import in the development of plants, specifically the process by which plants acquire photosynthetic competence. These studies incorporate molecular genetic techniques in Arabidopsis thaliana to investigate the diversity of Toc-Tic complexes and define the roles of these complexes in the selective import of proteins at different developmental stages.