Elucidation of the biochemical mechanism of glycogen phosphorylation in Escherichia coli

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dc.contributor.advisor Lloyd, J. R. en_ZA
dc.contributor.advisor Kossmann, J. M. en_ZA
dc.contributor.author Nepembe, Mehafo, Ndafapawa en_ZA
dc.contributor.other University of Stellenbosch. Faculty of Agrisciences. Dept. of Genetics. Institute for Plant Biotechnology.
dc.date.accessioned 2009-12-11T15:03:52Z en_ZA
dc.date.accessioned 2010-06-01T08:51:14Z
dc.date.available 2009-12-11T15:03:52Z en_ZA
dc.date.available 2010-06-01T08:51:14Z
dc.date.issued 2009-12
dc.identifier.uri http://hdl.handle.net/10019.1/2524
dc.description Thesis (MSc (Genetics. Plant Biotechnology)--University of Stellenbosch, 2009.
dc.description.abstract ENGLISH ABSTRACT: Glycogen was isolated from E. coli and analysed for the amount of phosphate present within it. It was confirmed that a significant proportion of the glucose residues were phosphorylated at the C6 position. This glycogen phosphate was found also in both glgb- (glycogen branching enzyme) and glgp- (glycogen phosphorylase enzyme) mutants, demonstrating that a mechanism for phosphate incorporation that does not involve GlgP alone, and which is capable of incorporating phosphate into linear glucans could exist. The degree of phosphorylation depended on the amount of phosphate present in the media, which less being incorporated in media where phosphate was reduced. Screening for glycogen phosphorylating genes using a E. coli genomic library in a functional expression system identified the malP gene as a possible candidate for incorporation of the phosphate at the C6 position. There was no difference, however, between the glycogen phosphate content of the mutant and wild type. Efforts were made to construct a malp-/glgp- double mutant, but these were unsuccessful. In addition the influence of plants and human proteins on yeast glycogen metabolism was also investigated. These proteins have been demonstrated to have an effect on starch or glycogen in humans, plant and E. coli, but the data from this study indicated that this was not the case in yeast. en_ZA
dc.description.abstract AFRIKAANSE OPSOMMING: Glikogeen, wat geisoleer was uit E.coli was geanaliseer vir fosfaat inhoud daarin. Daar was gevind dat `n beduidende proporsie van die glukose residue gefosforileerd was op die C6 posisie. Hierdie gefosforileerde glikogeen was ook gevind in glg- (glikogeen vertakkingsensieme) en glgp- (glikogeen fosforileringsensieme) mutante wat daarop dui dat `n meganisme vir fosforilering bestaan was nie slegs aangewese is op die aktiwiteit van GlgP nie, en om fosfaat te inkorporeer in linêre glukane. Die graad van fosforilering was ook afhanklik van die hoeveelheid fosfaat teenwoordig in die medium, met gevolglik minder wat geinkorporeer kan word in medium waar fosfaat verminderd was. Seleksie-gebaseerde ondersoeking vir fosforileringsensieme van glikogeen deur gebruik te maak van E. coli genomiese biblioteke in `n funksionele uitdrukkingssisteem het die malP geen geidentifiseer as een van die moontlike kandidate wat verantwoordelik kan wees vir inkorporering van fosfaat in the C6 posisie. Daar was egter geen verskil in die fosfaat inhoud van glikogeen tussen die wilde tipe en die mutante. Pogings wat aangewend is om `n malp-/glgpdubbel mutant te konstrueer was onsuksesvol. Verder is die invloed van plant en mens proteine op gis glikogeen ook bestudeer. Vroeër is aangetoon dat hierdie proteine `n invloed op stysel en glikogeen het in mense, plante en E. coli, maar data van hierdie studie toon aan dat dit nie die geval in gis is nie. en_ZA
dc.language.iso en en_ZA
dc.publisher Stellenbosch : University of Stellenbosch
dc.subject Theses -- Plant biotechnology en_ZA
dc.subject Dissertations -- Plant biotechnology
dc.subject.lcsh Glycogen phosphorylase en_ZA
dc.subject.lcsh Phosphorylation en_ZA
dc.subject.lcsh Escherichia coli en_ZA
dc.subject.other Genetics en_ZA
dc.subject.other Institute for Plant Biotechnology en_ZA
dc.title Elucidation of the biochemical mechanism of glycogen phosphorylation in Escherichia coli en_ZA
dc.type Thesis en_ZA
dc.rights.holder University of Stellenbosch


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