Role of Noise‑Induced Cellular Variability in Saccharomyces cerevisiae During Metabolic Adaptation: Causes, Consequences and Ramifications

Abstract

The concept of genetic determinism as illustrated by the metaphors
such as ‘genetic blueprint’, or ‘genetic program’ had its beginning
immediately after the rediscovery of growth lag observed when
bacteria were exposed to a mixture of glucose and galactose or lactose.
This concept got reinforced with the discovery of the mechanisms of how
lactose activates the transcription of lac operon of E. coli. According to
this doctrine, genetically identical cells exposed to the same environment
respond in equal measure. However, studies carried out in the past
two decades in organisms ranging from prokaryotes to eukaryotes, have
clearly established that genetically identical cells need not necessarily
respond in an identical fashion when exposed to a given environment. It
has now become amply clear that organisms can stochastically switch
from one physiological state to the other, thereby resulting in a phenotypically
heterogeneous population. Such exhibition of heterogeneity by
a population has been, in several contexts, shown to be beneficial in a
temporally changing environment. In this review, we have discussed how
individual cells of a genetically identical population of Saccharomyces
cerevisiae remain fit by exploiting this fascinating phenomenon of stochastic
switching from one metabolic state to the other when exposed to
glucose and galactose, as a source of carbon and energy. We suggest
that this inherent stochastic switching seems to have been exploited for
an adaptive response in a fluctuating environment.