Heterogeneous Molecular Dynamics Revealed through Live, Single-Cell Imaging

The study of the dynamic motion of single molecules or ensembles of molecules within cells can lend information as to those molecules’ activity or function. Here, we investigate the cell wall synthetic process of Bacillus subtilis in order to elucidate the mechanisms behind construction of the primary encoder of cell shape in this organism. Using fluorescence correlation spectroscopy, a technique we employ alongside small-molecule antibiotic perturbations, we probe molecular motion of the enzymes and filaments involved in cell wall construction. The known functions and targets of these antibiotics allow the inference of the specific roles of individual proteins involved in the cell wall synthetic complex based on the changes of motion we see of these proteins. This fluorescence imaging procedure will define a platform for imaging-based systems biology which can be applied in a general manner to genetically-tractable organisms to elucidate the functional roles of a host of complexes involved in various cellular processes.