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Perturbation of the interaction between Gal4p and Gal80p of the S accharomyces cerevisiae GAL switch results in altered responses to galactose and glucose
Author(s) -
Das Adhikari Akshay Kumar,
Qureshi Mohd. Tanvir,
Kar Rajesh Kumar,
Bhat Paike Jayadeva
Publication year - 2014
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.12757
Subject(s) - biology , saccharomyces cerevisiae , microbiology and biotechnology , genetics , signal transduction , galactokinase , gene , escherichia coli
Summary In S . cerevisiae , following the W hole G enome D uplication ( WGD ), GAL1 ‐encoded galactokinase retained its signal transduction function but lost basal expression. On the other hand, its paralogue GAL3 , lost kinase activity but retained its signalling function and basal expression, thus making it indispensable for the rapid induction of the S . cerevisiae GAL switch. However, a gal3 Δ strain exhibits delayed growth kinetics due to the redundant signalling function of GAL1 . The subfunctionalization between the paralogues GAL1 and GAL3 is due to expression divergence and is proposed to be due to the alteration in the Upstream Activating Sequences ( UAS G ). We demonstrate that the GAL switch becomes independent of GAL3 by altering the interaction between Gal4p and Gal80p without altering the configuration of UAS G . In addition to the above, the altered switch of S . cerevisiae loses ultrasensitivity and stringent glucose repression. These changes caused an increase in fitness in the disaccharide melibiose at the expense of a decrease in fitness in galactose. The above altered features of the Sc GAL switch are similar to the features of the GAL switch of K . lactis that diverged from S . cerevisiae before the WGD .