Nucleoid associated proteins maintain the architecture of the bacterial chromosome and regulate gene expression, hinting that their role as transcription factors may involve local three-dimensional... Show moreNucleoid associated proteins maintain the architecture of the bacterial chromosome and regulate gene expression, hinting that their role as transcription factors may involve local three-dimensional chromosome re-modelling. This dissertation provides the first evidence to support this hypothesis. Using ensemble RT-qPCR and 3C-qPCR, in addition to in vivo and in vitro single molecule fluorescence microscopy techniques, the interplay between the expression of the H-NS-regulated, osmosensitive proVWX operon of Escherichia coli and structural re-modelling of the operon is shown. The formation of a loop anchored between the P2 promoter of proVWX and the terminus of the operon represses its expression. Destabilization of the loop activates transcription. The model presented in this thesis provides clues for how H-NS and H-NS-like proteins may regulate the expression of other operons and genes within their regulons. Show less
The effective volume occupied by the genomes of all forms of life far exceeds that of the cells in which they are contained. Therefore, all organisms have developed mechanisms for compactly... Show more The effective volume occupied by the genomes of all forms of life far exceeds that of the cells in which they are contained. Therefore, all organisms have developed mechanisms for compactly folding and functionally organizing their genetic material. H-NS, a bacterial DNA compaction protein, is a prime example of a protein that is functionally modulated in response to environmental cues. These cues are translated into adapted gene expression patterns. We delve into the mechanisms underlying DNA compaction and its adaptation to environmental stimuli and explore the complex and subtle modulation of these diverse, yet difficult-to-study, structures. Show less
