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Nucleoid associated proteins: how they alter DNA topology and influence gene expression

Main researcher: Gary Rowley; Sacha Lucchini

Bacterial nucleoid-associated proteins function to package and organise the nucleoid. These proteins have the ability to alter the topology of the DNA by bending it and altering the levels of supercoiling. DNA is a dynamic molecule and the expression of many of the genes encoded within are sensitive to changes in the way that the DNA is twisted or bent.

Domain structure of H-NS protein

Schematical domain structure of H-NS

Many genes that are important in enabling the bacteria to adapt to changes in their environment are sensitive to such topologial changes in DNA structure.

Why are some promotors sensitive to DNA supercoiling?

Why are some promoters sensitive to DNA supercoiling?

The precise spacing between the -35 and the -10 regions determines whether a promotor becomes activated following the introduction of additional negative supercoiling or relaxation of the DNA.


The nucleoid-associated proteins act as global regulators, to transduce environmental signals by mechanisms that remain poorly understood, but involve changes in DNA topology.

DNA supercoiling in a wild-type and hns mutant strain of Escherichia coli

DNA supercoiling in a wild-type and hns mutant strain of Escherichia coli.

We are studying how proteins such as H-NS, Fis and StpA act to control DNA topology and gene expression, with a particular emphasis on their impact upon virulence genes in Salmonella and pathogenic strains of Escherichia coli.




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