Regulation of the speC gene encoding ornithine decarboxylase in Escherichia coli by putrescine, spermidine and cAMP

Simple item page
dc.contributor.authorPeters-Weigel, Sandra M.en
dc.contributor.departmentVeterinary Medical Sciencesen
dc.date.accessioned2014-03-14T21:43:02Zen
dc.date.adate2009-08-18en
dc.date.available2014-03-14T21:43:02Zen
dc.date.issued1993en
dc.date.rdate2009-08-18en
dc.date.sdate2009-08-18en
dc.description.abstractIn Escherichia coli, the speC gene encodes biosynthetic ornithine decarboxylase (ODC), an enzyme that catalyzes the decarboxylation of ornithine to produce putrescine. The two polyamines, putrescine and spermidine, and the cyclic AMP (CAMP) - cAMP receptor protein (CRP) are known to inhibit the expression of ODC via undefined mechanisms. A single copy of the speC’-lacZ fusion plasmid pOL-1, containing an 843 base pair fragment including the spec promoter, was transferred to the E. coli CB806 chromosome to create E. coli λCBOL. In cell-free extracts prepared from E. coli λCBOL supplemented with cAMP, putrescine, or spermidine, the B-galactosidase activity encoded by the speC’-lacZ fusion was compared to the ODC activity encoded by spec. Only cyclic AMP and putrescine repressed the speC’-lacZ fusion. Cyclic AMP, putrescine, and spermidine all repressed the spec gene. A 444 bp AluI restriction fragment, containing a putative CRP binding site and a downstream open reading frame (ORF2) present on the strand complementary to speC, was fused to lacZ to create a transcriptional fusion, pCC2L. Analysis of E. coli CB806/pCC2L revealed that there was no detectable β8- galactosidase activity from the ORF2-lacZ fusion. However, promoter activity was detected in the opposite direction (3’ to 5’) of ORF2 as alkaline phosphatase activity, encoded on the same plasmid, increased in the presence of CAMP. A 678 bp DraI-AatII fragment, containing the CRP binding site and an adjacent open reading frame (ORF3) present on the speC coding strand, was subcloned into plasmid pBR322 to create pBCR. In the presence of 10 mM cAMP, E. coli CB806/pBCR exhibited an 18% inhibition in ODC activity encoded by spec. It is proposed that ORF3 encodes a protein that represses speC in the presence of CAMP.en
dc.description.degreeMaster of Scienceen
dc.format.extentix, 74 leavesen
dc.format.mediumBTDen
dc.format.mimetypeapplication/pdfen
dc.identifier.otheretd-08182009-040534en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-08182009-040534/en
dc.identifier.urihttp://hdl.handle.net/10919/44299en
dc.language.isoenen
dc.publisherVirginia Techen
dc.relation.haspartLD5655.V855_1993.P4768.pdfen
dc.relation.isformatofOCLC# 31482736en
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subject.lccLD5655.V855 1993.P4768en
dc.subject.lcshCyclic adenylic aciden
dc.subject.lcshEscherichia coli -- Geneticsen
dc.subject.lcshOrnithine decarboxylaseen
dc.subject.lcshPutrescineen
dc.subject.lcshSpermidineen
dc.titleRegulation of the speC gene encoding ornithine decarboxylase in Escherichia coli by putrescine, spermidine and cAMPen
dc.typeThesisen
dc.type.dcmitypeTexten
thesis.degree.disciplineVeterinary Medical Sciencesen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

Files

Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
LD5655.V855_1993.P4768.pdf
Size:
7.04 MB
Format:
Adobe Portable Document Format
Description:
Download

Collections

Masters Theses