الفهرس 
Chapter I Identification of VfrH in P. putida and Determining its Role in the Expression of pca GenesOnly 14 pages are availabe for public view
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Abstract
In P~elldo.monas put~da (P. putida), aromatic hydrocarbons can be degraded into harmless compounds via the ~-ketoadipate pathway, which consists 0 f the cat branch and the pea branch. The cat branch merges with the pea branch at the level of the BBketoadipate enol lactone, and the pea gene’products s’ubsequently complete the degradation process. PcaR is the positive activator of the pea branch. Tn the presence of ~-ketoadipate, PcaR binds upstream to each promoter and activates the transcription of the pea genes. PcaR, however, is a negative regulator of its own transcription. Until recently, no positive regulator of the peaR gene had been identi fled. By searching the sequence upstream of the peaR promoter, a potential cyclic AMP receptor-binding protein consensus sequence (CCS) was found. Furthermore, a BLAST search of the P. [JlItida genome revealed an open reading frame that bore signi flcant homology to both the cyclic AMP receptor-binding protein (CRP) and the virulence factor regulator (Vfr) homologue. Preliminary investigation revealed that Vfr has a positive role in the expression of cloned pea genes of P. plilida as, in the absence ofVfr, the expression of pea genes is completely undetectable. Inactivation of the Vfr-like ORF on the P. pl/lida chromosome was undertaken using transposon mutagenesis. Investigations revealed that the absence of this ”VfrH” locus had a negative effect on P. pUlida growth, metabolism and motility suggesting that VfrH, like its counterpart, acts as a global regulator of gene expression. VfrH was also shown to have an important role in the expression of pea
genes of P. plltida through its effect on peaR expression. Furthermore, VrrH was able to
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