Gene regulation by H-NS as a function of growth conditions depends on chromosomal position in Escherichia coli.
Bottom Line: Our results show that the activity of the Phns promoter depends on whether it is placed within the AT-rich regions of the genome that are known to be bound preferentially by H-NS.This modulation of gene expression moreover depends on the growth phase and the growth rate of the cells, reflecting the changes taking place in the relative abundance of different nucleoid proteins and the inherent heterogeneous organization of the nucleoid.Genomic position can thus play a significant role in the adaptation of the cells to environmental changes, providing a fitness advantage that can explain the selection of a gene's position during evolution.
Affiliation: LBPA, UMR 8113 du CNRS, Ecole Normale Supérieure de Cachan, Cachan, France School of Engineering and Science, Jacobs University Bremen, Bremen, Germany.Show MeSH
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Mentions: Schematic representation of the Phns promoter and of the insertions in the E. coli chromosome. (A) The boxes indicate the binding sites for different proteins in the Phns promoter region (black for FIS, gray for H-NS, white for CspA) as derived from the literature (La Teana et al. 1991; Ueguchi et al. 1993; Falconi et al. 1996). Stars indicate the H-NS high-affinity DNA binding sites (Lang et al. 2007). The -10, -35 regions and the transcription starting site, +1, also are annotated. (B) The promoter-yfp unit is flanked by two T1 terminators from the E. coli rrnB coding sequence. (C) Representation of the six different mirror sites on the E. coli chromosome in which the yfp gene was inserted under the control of the Phns promoter next to the gene conferring resistance to chloramphenicol. The symbols used here are the ones used to indicate these positions in Figure 2B, Figure 5 and Supporting Information, Figure S6. Details about the insertion positions can be found in Table 1. CspA, Cold shock protein A; FIS, factor for inversion stimulation; H-NS, histone-like nucleoid-structuring protein.
Affiliation: LBPA, UMR 8113 du CNRS, Ecole Normale Supérieure de Cachan, Cachan, France School of Engineering and Science, Jacobs University Bremen, Bremen, Germany.