Some organisms, such as E. coli, previously thought to be dividing via symmetrical division were shown to exhibit heterogeneous phenotypes even within isogenic populations growing in homogeneous and constant environments. This significant cell-to-cell phenotypic heterogeneity has been hypothesised to be resulting from unequal distribution of cellular components. Such paradigm assumes intracellular asymmetry which may either rise from passive molecule segregation or localizing mechanisms.
In this work, we coupled a synthetic approach with lab-on-chip microscopy to control protein segregation in E. coli and investigate the resulting phenotypic implications.
To this end, we fused different proteins to an ionic peptide that self-assembles at the cells’ poles via nucleoid macromolecular crowding effect. We demonstrated their constant asymmetric segregation during numerous divisions in microfluidics using time-lapse microscopy. We also showed retained enzymatic activity in vivo by clustering the aminoglycoside-resistance enzyme (APH(3′)-IIIa) which allowed for asymmetric resistance to Kanamycin within a microcolony lineage.
Our controlled and quantitative approach to protein segregation not only represents a way to cluster proteins and thus favor metabolic channeling to differentiate monoclonal population – but also is a new tool allowing the study of fitness landscape governed by asymmetric division both at the single cell and the population level.