Effects of nucleoid-associated proteins on bacterial chromosome structure and gene expression

Bacterial nucleoid-associated proteins play a key role in the organisation, replication, segregation, repair and expression of bacterial chromosomes. Here, we review some recent progress in our understanding of the effects of these proteins on DNA and their biological role, focussing mainly on Escherichia coli and its chromosome. Certain nucleoid-associated proteins also regulate transcription initiation at specific promoters, and work in concert with dedicated transcription factors to regulate gene expression in response to growth phase and environmental change. Some specific examples, involving the E. coli IHF and Fis proteins, that illustrate new principles, are described in detail.