Control of the Asymmetric Segregation of Proteins at Division Thanks to a Self-Assembling Peptide

Asymmetric division may give rise to daughter cells with different fates. It often results from the unequal distribution of cellular components due to either random segregation of diffusive molecules or as a result of a localizing mechanism, placing molecules in specific locations within the cell prior to division. Unequal distribution of cellular components plays an important mechanistic role in a wide range of systems such as stem cells differentiation and renewal, bacterial sporulation control, antibiotic persistence, diauxie, and aging.

So far, most of asymmetric division studies were mostly observational and at best measured the degree of asymmetry using single-cell microscopy. We go one step further and use a synthetic approach in order to actively control the distribution of specific cellular components. By fusing proteins to a ionic self-assembling peptide (ELK16) we took advantage of the nucleoid macromolecular crowding effect to localize slowly diffusing, big assemblies at E. coli's pole.

We were then able to observe their asymmetric segregation during several divisions using time-lapse microscopy and microfluidic systems.We show that fused enzymatic activity is retained in vivo. As example, inducing asymmetry of the aminoglycoside-resistance enzyme (APH(3')-IIIa), resulted in polar segregation where only cells containing the enzyme cluster grew and survived multiple generations in the presence of the antibiotics (e.g. Kanamycin). In this work we created and characterized a useful tool to control the segregation of proteins inside E. coli, enabling the study of the fitness landscape governed by asymmetric division both at the single cell and at the population level. Moreover this might be used as a tool to cluster enzymes in order to favor metabolic channeling as recently shown as well as a way to differentiate monoclonal cell population.