Dynamics of SIN Asymmetry Establishment
Figure 2
Behavior of the minimal molecular model of SIN asymmetry establishment.
(A) A small bias in Byr4 binding to SPB is enough to establish asymmetry from an initial condition corresponding to metaphase-anaphase transition. Solid lines for molecules at old SPB, dashed lines for molecules at new SPB, time in arbitrary units. (B–E) Timing of transition (reaching the inflection point in the SINNew curve) greatly depends on total level of each of the investigated proteins (plotted on a log2 scale). In each plot the basal (wild type) parameter is normalized to 1 (dashed lines) and the final phenotype of the effect of increase and decrease are noted with the multinucleate and multiseptate S. pombe cartoons. SIN level cannot be varied in either direction (A), Byr4 cannot be increased, while major reduction has also a deleterious effect. (B) Cdc11 and SIP can be changed also in small regimes (C,D). The observed multiseptate phenotype at reduced Cdc11 levels might come from the fact that we start simulations with an initial mitotic high SIN state, which might not be even reached in this mutant, while the multinucleate phenotype of Cdc11 overexpression contradicts literature data [10], [34].