scholarly journals Molecular Characterization of the PhoP-PhoQ Two-Component System in Escherichia coli K-12: Identification of Extracellular Mg2+-Responsive Promoters

1999 ◽  
Vol 181 (17) ◽  
pp. 5516-5520 ◽  
Author(s):  
Akinori Kato ◽  
Hiroyuki Tanabe ◽  
Ryutaro Utsumi
Keyword(s):  
Escherichia Coli ◽  
Direct Repeat ◽  
Two Component System ◽  
Transcription Start ◽  
Promoter Regions ◽  
S1 Nuclease ◽  
Transcription Start Sites ◽  
Two Component ◽  
K 12

ABSTRACT We identified Mg2+-responsive promoters of thephoPQ, mgtA, and mgrB genes ofEscherichia coli K-12 by S1 nuclease analysis. Expression of these genes was induced by magnesium limitation and depended on PhoP and PhoQ. The transcription start sites were also determined, which allowed us to find a (T/G)GTTTA direct repeat in their corresponding promoter regions.

scholarly journals Identification and Molecular Characterization of the Mg2+ Stimulon of Escherichia coli

2003 ◽  
Vol 185 (13) ◽  
pp. 3696-3702 ◽  
Author(s):  
Shu Minagawa ◽  
Hiroshi Ogasawara ◽  
Akinori Kato ◽  
Kaneyoshi Yamamoto ◽  
Yoko Eguchi ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Direct Repeats ◽  
Two Component System ◽  
S1 Nuclease ◽  
Component System ◽  
Dnase I Footprinting ◽  
Two Component

ABSTRACT Transcription profile microarray analysis in Escherichia coli was performed to identify the member genes of the Mg2+ stimulon that respond to the availability of external Mg2+ in a PhoP/PhoQ two-component system-dependent manner. The mRNA levels of W3110 in the presence of 30 mM MgCl2, WP3022 (phoP defective), and WQ3007 (phoQ defective) were compared with those of W3110 in the absence of MgCl2. The expression ratios of a total of 232 genes were <0.75 in all three strains (the supplemental data are shown at http://www.nara.kindai.ac.jp/nogei/seiken/array.html ), suggesting that the PhoP/PhoQ system is involved directly or indirectly in the transcription of these genes. Of those, 26 contained the PhoP box-like sequences with the direct repeats of (T/G)GTTTA within 500 bp upstream of the initiation codon. Furthermore, S1 nuclease assays of 26 promoters were performed to verify six new Mg2+ stimulon genes, hemL, nagA, rstAB, slyB, vboR, and yrbL, in addition to the phoPQ, mgrB, and mgtA genes reported previously. In gel shift and DNase I footprinting assays, all of these genes were found to be regulated directly by PhoP. Thus, we concluded that the phoPQ, mgrB, mgtA, hemL, nagA, rstAB, slyB, vboR, and yrbL genes make up the Mg2+ stimulon in E. coli.

scholarly journals Negative Regulation of DNA Repair Gene (ung) Expression by the CpxR/CpxA Two-Component System in Escherichia coli K-12 and Induction of Mutations by Increased Expression of CpxR

2004 ◽  
Vol 186 (24) ◽  
pp. 8317-8325 ◽  
Author(s):  
Hiroshi Ogasawara ◽  
Jun Teramoto ◽  
Kiyo Hirao ◽  
Kaneyoshi Yamamoto ◽  
Akira Ishihama ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
In Vitro Transcription ◽  
Negative Regulation ◽  
Two Component System ◽  
Repair Gene ◽  
Component System ◽  
Dna Repair Gene ◽  
Two Component ◽  
K 12

ABSTRACT In Escherichia coli K-12 overexpressing CpxR, transcription of the ung gene for uracil-DNA glycosylase was repressed, ultimately leading to the induction of mutation. Gel shift, DNase I footprinting, and in vitro transcription assays all indicated negative regulation of ung transcription by phosphorylated CpxR. Based on the accumulated results, we conclude that ung gene expression is negatively regulated by the two-component system of CpxR/CpxA signal transduction.

The curli biosynthesis regulator CsgD co-ordinates the expression of both positive and negative determinants for biofilm formation in Escherichia coli

Microbiology ◽  
2003 ◽  
Vol 149 (10) ◽  
pp. 2847-2857 ◽  
Author(s):  
Eva Brombacher ◽  
Corinne Dorel ◽  
Alexander J. B. Zehnder ◽  
Paolo Landini
Keyword(s):  
Escherichia Coli ◽  
Biofilm Formation ◽  
Regulatory System ◽  
Multicopy Plasmid ◽  
Transcription Activator ◽  
Transcription Start ◽  
Promoter Regions ◽  
E Coli ◽  
Two Component ◽  
Extracellular Structures

Production of curli, extracellular structures important for biofilm formation, is positively regulated by OmpR, which constitutes with the EnvZ protein an osmolarity-sensing two-component regulatory system. The expression of curli is cryptic in most Escherichia coli laboratory strains such as MG1655, due to the lack of csgD expression. The csgD gene encodes a transcription activator of the curli-subunit-encoding csgBA operon. The ompR234 up-mutation can restore csgD expression, resulting in curli production and increased biofilm formation. In this report, it is shown that ompR234-dependent csgD expression, in addition to csgBA activation during stationary phase of growth, stimulates expression of the yaiC gene and negatively regulates at least two other genes, pepD and yagS. The promoter regions of these four genes share a conserved 11 bp sequence (CGGGKGAKNKA), necessary for csgBA and yaiC regulation by CsgD. While at both the csgBA and yaiC promoters the sequence is located upstream of the promoter elements, in both yagS and pepD it overlaps either the putative −10 sequence or the transcription start point, suggesting that CsgD can function as both an activator and a repressor. Adhesion experiments show that csgD-independent expression of both yagS and pepD from a multicopy plasmid negatively affects biofilm formation, which, in contrast, is stimulated by yaiC expression. Thus it is proposed that CsgD stimulates biofilm formation in E. coli by contemporary activation of adhesion positive determinants (the curli-encoding csg operons and the product of the yaiC gene) and repression of negative effectors such as yagS and pepD.

Characterization of broadly pleiotropic phenotypes caused by an hfq insertion mutation in Escherichia coli K-12

1994 ◽  
Vol 13 (1) ◽  
pp. 35-49 ◽  
Author(s):  
Ho-Ching Tiffany Tsui ◽  
Hon-Chiu Eastwood Leung ◽  
Malcolm E. Winkler
Keyword(s):  
Escherichia Coli ◽  
Insertion Mutation ◽  
K 12

scholarly journals Kinetic Characterization of the WalRKSpn (VicRK) Two-Component System of Streptococcus pneumoniae: Dependence of WalKSpn (VicK) Phosphatase Activity on Its PAS Domain

2010 ◽  
Vol 192 (9) ◽  
pp. 2346-2358 ◽  
Author(s):  
Alina D. Gutu ◽  
Kyle J. Wayne ◽  
Lok-To Sham ◽  
Malcolm E. Winkler
Keyword(s):  
Amino Acids ◽  
Streptococcus Pneumoniae ◽  
Phosphatase Activity ◽  
Pas Domain ◽  
Kinetic Characterization ◽  
Two Component System ◽  
Histidine Kinases ◽  
Component System ◽  
Two Component

ABSTRACT The WalRK two-component system plays important roles in maintaining cell wall homeostasis and responding to antibiotic stress in low-GC Gram-positive bacteria. In the major human pathogen, Streptococcus pneumoniae, phosphorylated WalR Spn (VicR) response regulator positively controls the transcription of genes encoding the essential PcsB division protein and surface virulence factors. WalR Spn is phosphorylated by the WalK Spn (VicK) histidine kinase. Little is known about the signals sensed by WalK histidine kinases. To gain information about WalK Spn signal transduction, we performed a kinetic characterization of the WalRK Spn autophosphorylation, phosphoryltransferase, and phosphatase reactions. We were unable to purify soluble full-length WalK Spn . Consequently, these analyses were performed using two truncated versions of WalK Spn lacking its single transmembrane domain. The longer version (Δ35 amino acids) contained most of the HAMP domain and the PAS, DHp, and CA domains, whereas the shorter version (Δ195 amino acids) contained only the DHp and CA domains. The autophosphorylation kinetic parameters of Δ35 and Δ195 WalK Spn were similar [Km (ATP) ≈ 37 μM; k cat ≈ 0.10 min−1] and typical of those of other histidine kinases. The catalytic efficiency of the two versions of WalK Spn ∼P were also similar in the phosphoryltransfer reaction to full-length WalR Spn . In contrast, absence of the HAMP-PAS domains significantly diminished the phosphatase activity of WalK Spn for WalR Spn ∼P. Deletion and point mutations confirmed that optimal WalK Spn phosphatase activity depended on the PAS domain as well as residues in the DHp domain. In addition, these WalK Spn DHp domain and ΔPAS mutations led to attenuation of virulence in a murine pneumonia model.

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