Activation of Escherichia coli rRNA Transcription by FIS during a Growth Cycle

Abstract

rRNA transcription in Escherichia coli is activated by the FIS protein, which binds upstream of rrnp 1promoters and interacts directly with RNA polymerase. Analysis of the contribution of FIS to rrn transcription under changing physiological conditions is complicated by several factors: the wide variation in cellular FIS concentrations with growth conditions, the contributions of several other regulatory systems to rRNA synthesis, and the pleiotropy of fis mutations. In this report, we show by in vivo footprinting and Western blot analysis that occupancy of the rrnBp 1 FIS sites correlates with cellular levels of FIS. We find, using two methods of measurement (pulse induction of a FIS-activated hybrid promoter and primer extension from an unstable transcript made fromrrnBp 1), that the extent of transcription activation by FIS parallels the degree of FIS site occupancy and therefore cellular FIS levels. FIS activates transcription throughout exponential growth at low culture density, butrrnp 1 transcription increases independently of FIS immediately following upshift, before FIS accumulates. These results support the model that FIS is one of a set of overlapping signals that together contribute to transcription fromrrnp 1 promoters during steady-state growth.

Large‐scale 13 C‐flux analysis reveals distinct transcriptional control of respiratory and fermentative metabolism in Escherichia coli

“…In contrast to B. subtilis, none of the E. coli mutants exhibited increased biomass productivity on its preferred substrate glucose, with the sole possible exception of Fis ( Figure 7A), whose deletion leads to an increase in stable rRNA synthesis (Appleman et al, 1998). On galactose, however, the previously identified mutants with higher galactose uptakes ( Figure 5A) clearly exhibited significantly increased biomass productivity, in particular Cra, IHF A, IHF B and NagC (Figure 7B), further supporting the conclusion that E. coli actively represses its galactose uptake rate at the expense of otherwise possible rapid growth.…”

Expression of the Fis protein is sustained in late‐exponential‐ and stationary‐phase cultures of Salmonella enterica serovar Typhimurium grown in the absence of aeration

“…Furthermore, SPI1 gene expression continues to depend on Fis even in late exponential phase with aeration (Kelly et al, 2004). This represents a point in the growth curve where Fis is poorly detected in E. coli (Ball et al, 1992;Appleman et al, 1998;Keane and Dorman, 2003), although approximately 10 000 Fis dimers were found to be present in an LT2 culture grown under aerated conditions to late logarithmic stage (Osuna et al, 1995). We hypothesized that the induction of SPI1 genes under non-aerated conditions could be due to the presence of the Fis protein.…”

A DNA architectural protein couples cellular physiology and DNA topology in Escherichia coli

“…To test this hypothesis we used two approaches. First, we carried out multiple cycles of dilution of cells in fresh medium -a procedure that supports a continuous expression of fis, such that high levels of FIS protein persist in the cell (Appleman et al, 1998). Using quantitative Western analysis, we found that the repeated cycles of dilution increased the difference in the amount of GyrA and GyrB proteins (to roughly threefold for both GyrA and GyrB after four to six dilution cycles versus 1.6-fold for GyrA and 1.77-fold for GyrB in a simple shift-up experiment) between the wild-type and fis cells (Fig.…”