Transcriptional Regulation of the Glycogen Phosphorylase-2 Gene in Dictyostelium discoideum

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dc.contributor.authorWarner, Nikitaen
dc.contributor.committeechairRutherford, Charles L.en
dc.contributor.committeememberWalker, Richard A.en
dc.contributor.committeememberGrabau, Elizabeth A.en
dc.contributor.committeememberWong, Eric A.en
dc.contributor.committeememberFalkinham, Joseph O. IIIen
dc.contributor.departmentBiologyen
dc.date.accessioned2014-03-14T20:16:32Zen
dc.date.adate1999-09-25en
dc.date.available2014-03-14T20:16:32Zen
dc.date.issued1999-08-27en
dc.date.rdate2000-09-25en
dc.date.sdate1999-09-21en
dc.description.abstractThe expression of the <I>glycogen phosphorylase- 2</I> gene (<I>gp2</I>) is initiated during early development and regulated by the extracellular morphogens cAMP and Differentiation Inducing Factor (DIF-1) [1-3]. Glycogen phosphorylase- 2 catalyzes the breakdown of glycogen reserves in developing cells to generate glucose precursors required for the synthesis of the end products of differentiation [4-6]. Thus, the expression of <I>gp2</I> is a significant event for cellular differentiation. The sequence of the <I>gp2</I> promoter, like other <I>Dictyostelium</I> promoters, has an AT-rich bias (88%) [7]. Previous deletional analyses of the promoter provided a map of the regions that contained transcriptional regulatory elements. The regions thus identified contained either "TAAAAATGGA" or C-rich repeat sequences [2]. These regions were dissected further by site-directed mutagenesis (SDM) to better define the physical boundaries of the regulatory elements. It was shown that the mutation of either one of the C-rich repeats resulted in a dramatic drop of about 95% in reporter gene levels. These data strongly suggested that both the C-rich repeats of <I>gp2</I> functioned as transcriptional regulatory elements. I have identified and purified a factor called TF2 that demonstrates a high specificity for a C-rich transcriptional regulatory element, the 5' C box. TF2 was first detected with electrophoretic mobility shift assays of DEAE chromatographic fractions of cell-free extracts. The specificity of TF2 for the 5' C box was tested by competition analysis using six other oligonucleotides. Purification of TF2 was achieved by ion-exchange chromatography, DNA affinity chromatography, gel filtration chromatography, and preparative SDS-PAGE. SDS-PAGE analysis indicated an apparent subunit molecular weight of 28 kDa. The apparent molecular weight of the native protein as estimated by gel filtration was about 53 kDa. This suggested that TF2 binds gp2 as a homodimer. A cDNA clone of the tf2 gene was provided by the Japanese <I>Dictyostelium</I> cDNA project. This allowed me to synthesize probes for Southern and Northern blot analyses. Southern blot analysis indicated that there is only one form of the <I>tf2</I> gene. Northern analysis showed little or no expression of <I>tf2</I> in undifferentiated cells. During development <I>tf2</I> expression increases up to a maximum at 8 h, then decreases in later stages. Attempts to disrupt the gene suggest that <I>tf2</I> mutation may be lethal.en
dc.description.degreePh. D.en
dc.identifier.otheretd-092199-122025en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-092199-122025/en
dc.identifier.urihttp://hdl.handle.net/10919/29050en
dc.publisherVirginia Techen
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dc.relation.haspartNWMAINBODY.PDFen
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dc.relation.haspartAbstractPart2.pdfen
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dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectTranscriptional regulationen
dc.subjectDictyostelium discoideumen
dc.subjectGlycogen phosphorylaseen
dc.subject3-oxoacyl-(acyl-carrier protein) reductaseen
dc.titleTranscriptional Regulation of the Glycogen Phosphorylase-2 Gene in <I>Dictyostelium discoideum</i>en
dc.typeDissertationen
thesis.degree.disciplineBiologyen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.leveldoctoralen
thesis.degree.namePh. D.en

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