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Title: Transcriptional regulation of the mra region in Escherichia coli
Author: Emmins, Robyn
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2006
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A single promoter designated Pmra, was previously identified upstream of the mra region. Pmra was reported to be essential for expression of the first nine genes of the mra region and may contribute to expression ftsQ, A, and Z at the distal end of this gene cluster. This study investigates potential mechanisms of transcriptional regulation at Pmra, in addition to the regulation of two newly identified promoters (Pmra2 and Pmra3) in the fruR-yabB intergenic region. Using lacZ reporter strains we determined that transcription from the Pmra promoters was inversely related to growth rate. Promoters Pmra1 and Pmra3 were the major contributors to the transcription of early genes in the mra region. Transcripts originating from these promoters were detected by RT-PCR to span at least as far as ftsL. The transcriptional regulator FIS was shown to bind several sites in the intergenic region, including sequences within the promoter regions of both Pmra2 and Pmra3. FIS caused a 3-fold repression of Pmra2 but had little effect on the transcriptional activity of Pmra3. It was noted that presence of the entire intergenic region caused a 4-fold repression of Pmra3, indicating that transcriptional regulators interact with the DNA upstream of this promoter. The 50S subunit ribosomal protein L3 was shown to bind upstream of Pmra3 . Pmra3 was also shown to be repressed by the cellular alarmone ppGpp which is produced as part of the stringent response and during slow growth or carbon starvation. It was not possible to delete Pmra3 from the chromosome suggesting that it may be essential for cell viability.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available