Perturbation of the interaction between Gal4p and Gal80p of the <i>Saccharomyces cerevisiae</i> GAL switch results in altered responses to galactose and glucose

Adhikari, Akshay Kumar Das; Qureshi, Mohd. Tanvir; Kar, Rajesh Kumar; Bhat, Paike Jayadeva

doi:10.1111/mmi.12846

Cited by 4 publications

(4 citation statements)

References 3 publications

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“…Accumulation of 2-DG-1-P causes toxicity thereby preventing the transformant from growing in gly/lac medium containing 2-DG. Transformants of gal3 bearing pYJM3 do not grow on gly/lac plates containing 2-DG (Figure 1A) as demonstrated previously (Das Adhikari et al 2014). In this study, we demonstrate that gal3 strain transformed with pCJM3, (single-copy Gal3p expression plasmid) is also unable to grow on gly/lac 2-DG plates (Figure 1A) as compared to the vector control (pCJM).…”

Section: A Wide Range Of Over-expression Of Gal3p Turns On the Gal Switch In The Absence Of Galactosesupporting

confidence: 87%

Multiple Conformations of Gal3 Protein Drive the Galactose-Induced Allosteric Activation of the GAL Genetic Switch of Saccharomyces cerevisiae

Kar

Kharerin

Padinhateeri

et al. 2017

Journal of Molecular Biology

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Gal3p is an allosteric monomeric protein that activates the GAL genetic switch of Saccharomyces cerevisiae in response to galactose. Expression of constitutive mutant of Gal3p or overexpression of wild-type Gal3p activates the GAL switch in the absence of galactose. These data suggest that Gal3p exists as an ensemble of active and inactive conformations. Structural data have indicated that Gal3p exists in open (inactive) and closed (active) conformations. However, a mutant of Gal3p that predominantly exists in inactive conformation and is yet capable of responding to galactose has not been isolated. To understand the mechanism of allosteric transition, we have isolated a triple mutant of Gal3p with V273I, T404A, and N450D substitutions, which, upon overexpression, fails to activate the GAL switch on its own but activates the switch in response to galactose. Overexpression of Gal3p mutants with single or double mutations in any of the three combinations failed to exhibit the behavior of the triple mutant. Molecular dynamics analysis of the wild-type and the triple mutant along with two previously reported constitutive mutants suggests that the wild-type Gal3p may also exist in super-open conformation. Furthermore, our results suggest that the dynamics of residue F237 situated in the hydrophobic pocket located in the hinge region drives the transition between different conformations. Based on this study, we suggest that conformational selection mechanism is the driving force in the allosteric transition of Gal3p, which may have implications in other signaling pathways involving monomeric proteins.

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Section: A Wide Range Of Over-expression Of Gal3p Turns On the Gal Switch In The Absence Of Galactosesupporting

confidence: 87%

Multiple Conformations of Gal3 Protein Drive the Galactose-Induced Allosteric Activation of the GAL Genetic Switch of Saccharomyces cerevisiae

Kar

Kharerin

Padinhateeri

et al. 2017

Journal of Molecular Biology

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“…For example, rare pairings of Constitutive GAL4 alleles and Uninducible GAL80 variants yielded Inducible phenotypes, an example of reciprocal sign epistasis 10 . Similar interactions have been previously described for distinct GAL4-GAL80 allele combinations [11][12][13] . Other combinations yielding viable Inducible or Leaky phenotypes included pairings of Uninducible GAL3 with Leaky GAL80 variants (Fig 2E and Fig S2).…”

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confidence: 76%

Harmonious genetic combinations rewire regulatory networks and flip gene essentiality

New

Lehner

2019

Preprint

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A key challenge in biology is to understand how mutations combine to alter phenotypes. Each genetic variant in a genome can have diverse effects, for example decreasing, increasing, inactivating, or changing the function of a protein or RNA. In contrast, systematic analyses of how mutations interact have typically used a single variant of each gene, most often a null allele. We therefore lack an understanding of how the full range of genetic variants that occur in individuals can interact. To address this shortcoming, we developed an approach to combine >5000 pairs of diverse mutations in a model regulatory network. The outcome of most mutation combinations could be accurately predicted by simple rules that capture the 'stereotypical' genetic interactions (epistasis) in the network. However, for individual genotypes, additional, unexpected pairwise and higher order genetic interactions can be important. These include 'harmonious' combinations of individually detrimental alleles that reconstitute alternative functional switches. Our results provide an overview of how the full spectra of possible mutations in genes interact and how these interactions can be predicted. Moreover, they illustrate the importance of rare genetic interactions for individuals, including the impact of higher order epistatic interactions that dramatically alter the consequences of inactivating genes. Main textHuman genomes contain millions of genetic variants. Each of these variants can have diverse effects, for example quantitatively increasing, decreasing or changing the activity of individual genes 1 .Understanding and predicting how the particular combination of variants present in each individual affects molecular processes and phenotypic traits is a fundamental challenge for human genetics and evolutionary biology 2 . To date, however, systematic analyses of how mutations in different genes combine to influence phenotypes have used only one or a few mutations in each gene, most often an inactivating null allele 3,4 . A more complete understanding of how mutations combine in individuals will require functionally diverse mutations in individual genes to be combined in large numbers 5 .The GAL regulatory (GALR) system from yeast is a promising model to begin such studies because it is mechanistically well-understood, has relatively few molecular players, and is an important model of gene network function and evolution 6,7 ( Fig 1A). This network is required for sensing the sugar galactose and then inducing transport (via Gal2) and the Leloir pathway proteins Gal1p, Gal7p, and Gal10p necessary to metabolize this sugar as a carbon source for growth. The core of this network consists of three regulatory genes and their protein products: GAL4, a transcriptional activator; GAL80, its repressor; and GAL3, which acts as a GAL sensor by inhibiting Gal80p as an activated Gal3p-Galactose-ATP complex 8 ( Fig 1A). The GAL1 locus, encoding the first Leloir enzyme galactokinase (GALK) Gal1p, is a paralog of GAL3 that can also effect galactose sensing....

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“…The following changes have been made to the article by Das Adhikari et al . (). First, a corrected version of Table is now included.…”

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confidence: 97%

Perturbation of the interaction between Gal4p and Gal80p of the Saccharomyces cerevisiae GAL switch results in altered responses to galactose and glucose

Adhikari

Qureshi

Kar

et al. 2014

Molecular Microbiology

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Perturbation of the interaction between Gal4p and Gal80p of the Saccharomyces cerevisiae GAL switch results in altered responses to galactose and glucose

Cited by 4 publications

References 3 publications

Multiple Conformations of Gal3 Protein Drive the Galactose-Induced Allosteric Activation of the GAL Genetic Switch of Saccharomyces cerevisiae

Multiple Conformations of Gal3 Protein Drive the Galactose-Induced Allosteric Activation of the GAL Genetic Switch of Saccharomyces cerevisiae

Harmonious genetic combinations rewire regulatory networks and flip gene essentiality

Perturbation of the interaction between Gal4p and Gal80p of the Saccharomyces cerevisiae GAL switch results in altered responses to galactose and glucose

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