Nanofluidic landscapes and precision microscopy for studying molecular processes in living cells

Micro- and nanofluidic devices combined with high-resolution quantitative imaging offer a variety of new possibilities to study single cells down to a nanometer-scale resolution. Here, I describe a study where we rely much on these new technological advances in elucidating the molecular mechanisms of bacterial cell division. We investigate how Escherichia coli bacteria are able reliably and accurately position their cell division proteins, i.e. the divisome, in normal and in irregularly shaped phenotypes. We use ‘squeezed’ E. coli in shallow nanofabricated channels [1] as an irregularly shaped phenotype and compare these cells to their normal rod-shaped counterparts. We study the roles of two molecular systems in this process - one consisting of MinCDE proteins and the other of the bacterial chromosome. We find that while Min proteins are effective in excluding cell division at the poles of rod-shaped bacteria, this inhibitory system becomes chaotic in more complicated cell shapes. Instead, we observe that localization of the divisome is highly anticorrelated with the complex pattern of chromosome distribution in squeezed E. coli cells [2]. We also show that in addition to chromosomal distribution the curvature of a cell’s plasma membrane is instrumental in the fine scale positioning of the divisome. We find that linear divisome complexes form on the circumference of the squeezed cells so that their line curvature is maximized.

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