PT  - JOURNAL ARTICLE
AU  - Morgan Delarue
AU  - Daniel Weissman
AU  - Oskar Hallatschek
TI  - A simple molecular mechanism explains multiple patterns of cell-size regulation
AID  - 10.1101/083725
DP  - 2016 Jan 01
TA  - bioRxiv
PG  - 083725
4099  - http://biorxiv.org/content/early/2016/10/26/083725.short
4100  - http://biorxiv.org/content/early/2016/10/26/083725.full
AB  - Increasingly accurate and massive data have recently shed light on the fundamental question of how cells maintain a stable size trajectory as they progress through the cell cycle. Microbes seem to use strategies ranging from a pure sizer, where the end of a given phase is triggered when the cell reaches a critical size, to pure adder, where the cell adds a constant size during a phase. Yet the biological origins of the observed spectrum of behavior remain elusive. We analyze a molecular size-control mechanism, based on experimental data from the yeast S. cerevisiae, that gives rise to behaviors smoothly interpolating between adder and sizer. The size-control is obtained from the titration of a repressor protein by an activator protein that accumulates more rapidly with increasing cell size. Strikingly, the size-control is composed of two different regimes: for small initial cell size, the size-control is a sizer, whereas for larger initial cell size, is is an imperfect adder. Our model thus indicates that the adder and critical size behaviors may just be different dynamical regimes of a single simple biophysical mechanism.