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Stochastic galactokinase expression underlies GAL gene induction in a GAL3 mutant of Saccharomyces cerevisiae

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Title Stochastic galactokinase expression underlies GAL gene induction in a GAL3 mutant of Saccharomyces cerevisiae
 
Creator KAR, RK
QURESHI, MT
DASADHIKARI, AK
ZAHIR, T
VENKATESH, KV
BHAT, PJ
 
Subject bimodality
incomplete penetrance
long-term adaptation
nongenetic heterogeneity
stochastic distribution
DUPLICATE GENES
KLUYVEROMYCES-LACTIS
FLUCTUATING ENVIRONMENTS
GAL4P-ACTIVATED GENES
SIGNAL-TRANSDUCTION
FEEDBACK LOOPS
YEAST
GALACTOSE
EVOLUTION
SWITCH
 
Description GAL1 and GAL3 are paralogous signal transducers that functionally inactivate Gal80p to activate the Gal4p-dependent transcriptional activation of GAL genes in Saccharomycescerevisiae in response to galactose. Unlike a wild-type strain, the gal3 strain shows delayed growth kinetics as a result of the signaling function of GAL1. The mechanism ensuring that GAL1 is eventually expressed to turn on the GAL switch in the gal3 strain remains a paradox. Using galactose and histidine growth complementation assays, we demonstrate that 0.3% of the gal3 cell population responds to galactose. This is corroborated by flow cytometry and microscopic analysis. The galactose responders and nonresponders isolated from the galactose-adapted population attain the original bimodal state and this phenotype is found to be as hard wired as a genetic trait. Computational analysis suggests that the log-normal distribution in GAL4 synthesis can lead to bimodal expression of GAL80, resulting in the bimodal expression of GAL genes. Heterozygosity at the GAL80 but not at the GAL1, GAL2 or GAL4 locus alters the extent of bimodality of the gal3 cell population. We suggest that the asymmetric expression pattern between GAL1 and GAL3 results in the ability of S.cerevisiae to activate the GAL pathway by conferring nongenetic heterogeneity.
 
Publisher WILEY-BLACKWELL
 
Date 2014-12-28T14:56:23Z
2014-12-28T14:56:23Z
2014
 
Type Article
 
Identifier FEBS JOURNAL, 281(7)1798-1817
1742-464X
1742-4658
http://dx.doi.org/10.1111/febs.12741
http://dspace.library.iitb.ac.in/jspui/handle/100/16809
 
Language English