Monday, February 25, 2013
Probing bacterial cell shape determination by watching the dynamics of synthetic enzymes
Ethan Garner, Assistant Professor, Department of Molecular and Cellular Biology, Harvard University
Rod-shaped bacteria elongate by the action of cell-wall synthetic enzymes. How the nanometer scale enzymatic activity of these proteins create micron scale order is unknown. We examine the motions of these synthetic enzymes and their associated cytoskeletal filaments by measuring protein dynamics at the single molecule level. These studies show us that these synthetic machines move in a processive, motor like fashion around the cell. We find that the motions of these complexes are independent, as they can pause and reverse, and also as nearby complexes move independently in both directions across one surface of the cell. Inhibition of cell wall synthesis with antibiotics or depletions in the cell wall synthesis stops motion, indicating the motions are powered by the enzymatic processes of cell wall synthesis. Our recent studies are working to understand the molecular mechanisms by which these machines are regulated, and how these independent, disconnected complexes cohere into a radial organization to give the cell rod shape.