Dr. Annkatrin Rose

Comparative Analysis of Long Coiled-coil Proteins of Plant Golgi and Chloroplast Membranes

Annkatrin Rose
Appalachian State University, Boone, NC 28608, USA

Cells exhibit a remarkable degree of spatial and temporal organization, for example in the form of structured compartments and targeted movements within the cell. A common feature of these processes is the involvement of long alpha-helical coiled-coil proteins. They provide cables and meshes in the cyto- and nucleoskeleton, molecular scaffolds that organize membrane systems and tissues, motors for movement, and the "cellular Velcro" to sequester other subcellular components to their assigned places within the cell. Proteins with extended coiled-coil domains and functioning as motor proteins, membrane tethering and vesicle transport proteins are absent from bacteria. This suggests that these eukaryotic-type coiled-coil proteins have developed to organize the increasingly complex processes of subcellular infrastructure maintenance and trafficking control of the larger eukaryotic cell. One example is a group of Golgi coiled-coil proteins involved in Golgi vesicle fusion and membrane stacking. Interestingly, similar coiled-coil proteins can be found in the chloroplasts of plants which are thought to have evolved from endosymbiotic prokaryotes. One such protein is MFP1, a eukaryotic-type coiled-coil protein encoded by the nuclear genome and targeted to the thylakoid membrane in chloroplasts. MFP1 is inserted into the membrane with a topology similar to Golgi proteins such as the golgin CASP. At least four structurally similar coiled-coil proteins with chloroplast targeting sequences can be identified in the Arabidopsis thaliana (mouse ear cress) genome. The presence of these proteins in chloroplasts may indicate the introduction of eukaryotic-type coiled-coil proteins encoded by the plant cell into the plastid after endosymbiosis.

Talk at the Science in the Mountains Meeting, Boone, NC, June 21-27, 2007.