Nucleoid associated proteins: how they alter
DNA topology and influence gene expression
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.
of H-NS protein
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?
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
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.