Stationary-phase-inducible "gearbox" promoters: differential effects of katF mutations and role of sigma 70

Abstract

Many of the changes in gene expression observed when Escherichia coli cells enter stationary phase are regulated at the level of transcription initiation. A group of stationary-phase-inducible promoters, known as "gearbox" promoter, display a characteristic sequence in the -10 region which differs greatly from the consensus sequence for sigma 70-dependent promoters. Here we describe our studies on the gearbox promoters bolAp1 and mcbAp, responsible for the temporally regulated transcription of bolA and the genes involved in the synthesis of the peptide antibiotic microcin B17, respectively. Deletion analysis of mcbAp demonstrated that the stationary-phase-inducible properties of this promoter are found in a DNA fragment extending from -54 to +11 bp, surrounding the transcriptional start site, and are separable from DNA sequences responsible for the OmpR-dependent stimulation of transcription of mcbAp. In vitro transcription studies indicate that the RNA polymerase holoenzyme involved in the transcription of mcbAp contains sigma 70. In this and an accompanying paper (R. Lange and R. Hengge-Aronis, J. Bacteriol. 173: 4474-4481, 1991), experiments are described which show that the product of katF, a global regulator of stationary-phase gene expression and a putative sigma factor, is required for the expression of bolAp1 fused to the reporter gene lacZ. In contrast, mcbAp appears to be negatively regulated by katF. We discuss the implications of these results for postexponential gene expression and the role of gearbox sequences in the regulation of promoter activity.

Cell Density-Dependent Gene Contributes to Efficient Seed Colonization by Pseudomonas putida KT2440

“…3), as is the case in the wild-type strain. This behavior is similar to what has been observed in growth phase-regulated, rpoS-independent promoters in E. coli (5). Intriguingly, when pME510 was introduced in mutant mus-5, a slight but consistent reduction in the maximal activity levels of the ddcA::lacZ fusion was observed (Fig.…”

The LetE Protein Enhances Expression of Multiple LetA/LetS-Dependent Transmission Traits by Legionella pneumophila

“…3). Starved E. coli adopt a coccoid shape through reductive division which requires RpoS-dependent genes such as bolA (9,26). Wild-type and letE mutant PE-phase cultures retain roughly constant CFU, but wild-type cells differentiate to form short rods while letE mutants continue to elongate in the PE phase, a phenomenon that may affect their OD in culture.…”

Diversification Rates Increase With Population Size and Resource Concentration in an Unstructured Habitat

“…These strains carry a bolATlacZ reporter fusion (Bohannon et al 1991). bolA gene expression is under control of the general regulatory protein RpoS (Hengge-Aronis 2000); maximal lacZ expression is dependent on wild-type alleles of rpoS.…”

“…Bacterial cultures: Following standard methods for longterm stationary phase culture of E. coli (Zambrano and Kolter 1996;Finkel et al 2000;Finkel 2006), all experiments used strains derived from ZK918, an E. coli K-12 (nonmating) strain, that carries a bolATlacZ reporter fusion to monitor the appearance of rpoS mutants within the populations (see below; Bohannon et al 1991). SF2054 and SF2055 are otherwise isogenic versions of ZK918, expressing resistance to either nalidixic acid (NalR) or streptomycin (StrR), respectively (Farrell and Finkel 2003).…”