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Title: Studies on gene expression in a pathogenic bacterium
Author: Islam, Shahidul Md.
ISNI:       0000 0004 2705 5319
Awarding Body: University of Birmingham
Current Institution: University of Birmingham
Date of Award: 2011
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The activity of the major pathogenicity determinant of enterohaemorrhagic Escherichia coli is primarily coordinated by expression of the LEE1 operon which is part of the locus of enterocyte effacement (LEE). The LEE1 operon regulatory region has been dissected. LEE-encoded transcription factor, GrlA, activates the LEE1 P1 promoter by binding to a target located within the 18 base pair spacer between the promoter 10 and 35 elements. Shortening this spacer to 17 base pairs increases P1 promoter activity and short-circuits GrlA dependent activation, suggesting that GrlA functions like MerR family transcription activators. It was also found that the LEE1 P1 promoter is overlapped by a cryptic promoter, designated P1A. A single base substitution in the P1 consensus -35 element unmasks P1A promoter activity. In contrast, P1A activity is much less when P1 is inactivated by a mutation in its -10 hexamer element. Hence, even when P1 is inactive, the consensus -35 element sequesters RNA polymerase and prevents its access to the P1A promoter. The LEE1 leader sequence also contains a mini-gene that encodes a dipeptide. Genetic studies showed that expression of this mini-gene is important for optimal expression of downstream genes.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QR Microbiology