Abstract
Diploid budding yeast (Saccharomyces cerevisiae) can adopt one
of several alternative differentiation fates in response to nutrient limitation,
and each of these fates provides distinct biological functions. When different
strain backgrounds are taken into account, these various fates occur in response
to similar environmental cues, are regulated by the same signal transduction
pathways, and share many of the same master regulators. I propose that the
relationships between fate choice, environmental cues and signaling pathways are
not Boolean, but involve graded levels of signals, pathway activation and
master-regulator activity. In the absence of large differences between
environmental cues, small differences in the concentration of cues may be
reinforced by cell-to-cell signals. These signals are particularly essential for
fate determination within communities, such as colonies and biofilms, where fate
choice varies dramatically from one region of the community to another. The lack
of Boolean relationships between cues, signaling pathways, master regulators and
cell fates may allow yeast communities to respond appropriately to the wide
range of environments they encounter in nature.
Collapse