Investigation of MAL gene regulation in Saccharomyces.
Item
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Title
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Investigation of MAL gene regulation in Saccharomyces.
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Identifier
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AAI3083716
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identifier
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3083716
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Creator
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Wang, Xin.
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Contributor
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Adviser: Corinne A. Michels
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Date
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2003
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Language
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English
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Publisher
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City University of New York.
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Subject
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Biology, Genetics | Biology, Molecular
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Abstract
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Maltose induction requires the maltose permease and the MAL-activator. But maltose permease does not appear to be a maltose sensor because we demonstrated that intracellular maltose is sufficient to induce MAL gene expression. PmSUC2 encodes a sucrose transporter from the dicot plant Plantago major that exhibits no significant sequence homology to maltose permease and is capable of transporting maltose when expressed in Saccharomyces. Introduction of PmSUC2 restores maltose inducible MAL gene expression to a maltose permease null mutant and this induction requires the MAL-activator. Furthermore, constitutive overexpression of either MAL61 maltose permease or PmSUC2 suppresses the noninducible phenotype of a defective mal13 MAL-activator allele, suggesting that this suppression is solely a function of maltose transport activity and is not specific to the sequence of the permease.;A genetic selection for constitutive MAL mutants was carried out to identify additional regulators. 29 recessive mutants were identified and fall into at least two complementation groups: rgr1 (10 alleles) and sin4 (6 alleles). Both groups of mutants are pleiotropic and cause slow growth, flocculation and insensitiveness to glucose repression. Moreover, RGR1 and SIN4 repress the MAL gene expression in a common pathway.;Further genetic analysis was done to determine the roles of the Mediator complex in MAL gene regulation. RGR1 and SIN4 repress MAL gene expression independent of maltose signal pathway and do not act via Mig1/2 repressors. Each component of the Sin4 module plays a distinct role in regulating MAL gene expression. Gal11p is involved in both basal expression and induction. Pgd1p, and Med2p are required for maltose induction only. Additionally, the Swi/Snf complex is required for the full induction suggesting a role for chromatin remodeling in the activation of the MAL genes.;In summary, our results indicate that intracellular maltose is sufficient to induce MAL gene expression and maltose permease appears not to function as a maltose sensor. The Mediator complex is involved in controlling both basal and maltose-inducible MAL gene expression and each component of Sin4 module plays a distinct role in MAL gene regulation. The Swi/Snf complex is involved in maltose induction.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
