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Analysis of the transcriptional regulation of the tpr protease gene of porphyromonas gingivalis

University of British Columbia

The expression of Porphyromonas gingivalis W83 tpr protease gene is regulated at the transcription level by the nutritional environment. To investigate the regulation of tpr expression in P. gingivalis, we determined the sequence of the upstream region of tpr and by primer extension studies we determined that the transcription start sites were at two A residues 215 nucleotides upstream of the coding region. Computer analysis of the immediate upstream region did not find any consensus sequence to the -35 and -10 region of E. coli promoters. A tprr.lacZ reporter gene construct was introduced into P. gingivalis, the reporter gene expression is under the control of tpr promoter. Deletion mutations in the tpr upstream regions confirmed the promoter region to be the same as that determined by primer extension studies. Three identical direct repeats of 17 bp were identified in the upstream region of tpr. Deletion analysis of these repeats suggested they were involved in tpr regulation. Tpr expression was repressed by the addition of nutrients, such as brain heart infusion (BHI), trypticase peptone, bovine serum albumin (BSA) and gelatin. Single amino acids had little effect. BHI fractions of low molecular weight rich in proline, alanine and phenylalanine repressed tpr expression the most. The di-peptide phenylalanyl-phenylalanine repressed tpr expression. Heat shock, pH change and hemin starvation had little effect on tpr expression. The tpr

Thesis/Dissertation

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2009-06-02

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http://hdl.handle.net/2429/8607

Microbiology and Immunology

University of British Columbia

UBCV

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