scholarly journals Involvement of ςS in Starvation-Induced Transposition of Pseudomonas putidaTransposon Tn4652

2001 ◽  
Vol 183 (18) ◽  
pp. 5445-5448 ◽  
Author(s):  
Heili Ilves ◽  
Rita Hõrak ◽  
Maia Kivisaar
Keyword(s):  
Stationary Phase ◽  
Pseudomonas Putida ◽  
Sigma Factor ◽  
Mobile Element ◽  
Environmental Stresses ◽  
Mobile Elements ◽  
Present Evidence ◽  
Transpositional Activity ◽  
Specific Regulation

ABSTRACT Transpositional activity of mobile elements can be induced by different environmental stresses. Here, we present evidence that transposition of Tn4652 is elevated in stationary-phasePseudomonas putida and suppressed in an isogenic ςS-defective strain. We demonstrate that transcription from the Tn4652 transposase promoter is controlled by the stationary-phase-specific sigma factor ςS. To our knowledge, this is the first example of direct stationary-phase-specific regulation of a mobile element transposase. Data presented in this report support the idea that activation of transposition under stressful conditions could be an inducible process.

scholarly journals Effects of Combination of Different −10 Hexamers and Downstream Sequences on Stationary-Phase-Specific Sigma Factor ςS-Dependent Transcription in Pseudomonas putida

2000 ◽  
Vol 182 (23) ◽  
pp. 6707-6713 ◽  
Author(s):  
Eve-Ly Ojangu ◽  
Andres Tover ◽  
Riho Teras ◽  
Maia Kivisaar
Keyword(s):  
Stationary Phase ◽  
Pseudomonas Putida ◽  
Sigma Factor ◽  
Sigma Factors ◽  
Deficient Mutant ◽  
Wild Type ◽  
In Vivo Experiments ◽  
Silent Genes ◽  
Rna Polymerase Holoenzyme

ABSTRACT The main sigma factor activating gene expression, necessary in stationary phase and under stress conditions, is ςS. In contrast to other minor sigma factors, RNA polymerase holoenzyme containing ςS (EςS) recognizes a number of promoters which are also recognized by that containing ς70 (Eς70). We have previously shown that transposon Tn4652 can activate silent genes in starvingPseudomonas putida cells by creating fusion promoters during transposition. The sequence of the fusion promoters is similar to the ς70-specific promoter consensus. The −10 hexameric sequence and the sequence downstream from the −10 element differ among these promoters. We found that transcription from the fusion promoters is stationary phase specific. Based on in vivo experiments carried out with wild-type and rpoS-deficient mutant P. putida, the effect of ςS on transcription from the fusion promoters was established only in some of these promoters. The importance of the sequence of the −10 hexamer has been pointed out in several published papers, but there is no information about whether the sequences downstream from the −10 element can affect ςS-dependent transcription. Combination of the −10 hexameric sequences and downstream sequences of different fusion promoters revealed that ςS-specific transcription from these promoters is not determined by the −10 hexameric sequence only. The results obtained in this study indicate that the sequence of the −10 element influences ςS-specific transcription in concert with the sequence downstream from the −10 box.

scholarly journals Different Spectra of Stationary-Phase Mutations in Early-Arising versus Late-Arising Mutants of Pseudomonas putida: Involvement of the DNA Repair Enzyme MutY and the Stationary-Phase Sigma Factor RpoS

2002 ◽  
Vol 184 (24) ◽  
pp. 6957-6965 ◽  
Author(s):  
Signe Saumaa ◽  
Andres Tover ◽  
Lagle Kasak ◽  
Maia Kivisaar
Keyword(s):  
Stationary Phase ◽  
Pseudomonas Putida ◽  
Transcriptional Activation ◽  
Sigma Factor ◽  
Phenol Degradation ◽  
Test System ◽  
Growth Barriers ◽  
Mutational Processes ◽  
Sigma Factor Rpos ◽  
Selection Of

ABSTRACT Stationary-phase mutations occur in populations of stressed, nongrowing, and slowly growing cells and allow mutant bacteria to overcome growth barriers. Mutational processes in starving cells are different from those occurring in growing bacteria. Here, we present evidence that changes in mutational processes also take place during starvation of bacteria. Our test system for selection of mutants based on creation of functional promoters for the transcriptional activation of the phenol degradation genes pheBA in starving Pseudomonas putida enables us to study base substitutions (C-to-A or G-to-T transversions), deletions, and insertions. We observed changes in the spectrum of promoter-creating mutations during prolonged starvation of Pseudomonas putida on phenol minimal plates. One particular C-to-A transversion was the prevailing mutation in starving cells. However, with increasing time of starvation, the importance of this mutation decreased but the percentage of other types of mutations, such as 2- to 3-bp deletions, increased. The rate of transversions was markedly elevated in the P. putida MutY-defective strain. The occurrence of 2- to 3-bp deletions required the stationary-phase sigma factor RpoS, which indicates that some mutagenic pathway is positively controlled by RpoS in P. putida.

scholarly journals Regulation of the N-Acyl Homoserine Lactone-Dependent Quorum-Sensing System in Rhizosphere Pseudomonas putida WCS358 and Cross-Talk with the Stationary-Phase RpoS Sigma Factor and the Global Regulator GacA

2004 ◽  
Vol 70 (9) ◽  
pp. 5493-5502 ◽  
Author(s):  
Iris Bertani ◽  
Vittorio Venturi
Keyword(s):  
Quorum Sensing ◽  
Stationary Phase ◽  
Pseudomonas Putida ◽  
Family Member ◽  
Growth Phase ◽  
Sigma Factor ◽  
Response Regulator ◽  
Expression Profiles ◽  
Regulatory System ◽  
Homoserine Lactone

ABSTRACT Quorum sensing is a cell population-density dependent regulatory system which in gram-negative bacteria often involves the production and detection of N-acyl homoserine lactones (AHLs). Some Pseudomonas putida strains have been reported to produce AHLs, and one quorum-sensing locus has been identified. However, it appears that the majority of strains do not produce AHLs. In this study we report the identification and regulation of the AHL-dependent system of rhizosphere P. putida WCS358. This system is identical to the recently identified system of P. putida strain IsoF and very similar to the las system of Pseudomonas aeruginosa. It is composed of three genes, the luxI family member ppuI, the putative repressor rsaL, and the luxR family member ppuR. A genomic ppuR::Tn5 mutant of strain WCS358 was identified by its inability to produce AHLs when it was cross-streaked in close proximity to an AHL biosensor, whereas an rsaL::Tn5 genomic mutant was identified by its ability to overproduce AHL molecules. Using transcriptional promoter fusions, we studied expression profiles of the rsaL, ppuI, and ppuR promoters in various genetic backgrounds. At the onset of the stationary phase, the autoinducer synthase ppuI gene expression is under positive regulation by PpuR-AHL and under negative regulation by RsaL, indicating that the molecules could be in competition for binding at the ppuI promoter. In genomic rsaL::Tn5 mutants ppuI expression and production of AHL levels increased dramatically; however, both processes were still under growth phase regulation, indicating that RsaL is not involved in repressing AHL production at low cell densities. The roles of the global response regulator GacA and the stationary-phase sigma factor RpoS in the regulation of the AHL system at the onset of the stationary phase were also investigated. The P. putida WCS358 gacA gene was cloned and inactivated in the genome. It was determined that the three global regulatory systems are closely linked, with quorum sensing and RpoS regulating each other and GacA positively regulating ppuI expression. Studies of the regulation of AHL quorum-sensing systems have lagged behind other studies and are important for understanding how these systems are integrated into the overall growth phase and metabolic status of the cells.

scholarly journals Construction and Characterization of aMycobacterium tuberculosis Mutant Lacking the Alternate Sigma Factor Gene, sigF

2000 ◽  
Vol 68 (10) ◽  
pp. 5575-5580 ◽  
Author(s):  
Ping Chen ◽  
Rafael E. Ruiz ◽  
Qing Li ◽  
Richard F. Silver ◽  
William R. Bishai
Keyword(s):  
Stationary Phase ◽  
Sigma Factor ◽  
Type Strain ◽  
Wild Type Strain ◽  
Axenic Culture ◽  
Wild Type ◽  
Intracellular Growth ◽  
Factor Gene ◽  
Time To Death

ABSTRACT The alternate RNA polymerase sigma factor gene, sigF, which is expressed in stationary phase and under stress conditions in vitro, has been deleted in the virulent CDC1551 strain ofMycobacterium tuberculosis. The growth rate of the ΔsigF mutant was identical to that of the isogenic wild-type strain in exponential phase, although in stationary phase the mutant achieved a higher density than the wild type. The mutant showed increased susceptibility to rifampin and rifapentine. Additionally, the ΔsigF mutant displayed diminished uptake of chenodeoxycholate, and this effect was reversed by complementation with a wild-type sigF gene. No differences in short-term intracellular growth between mutant and wild-type organisms within human monocytes were observed. Similarly, the organisms did not differ in their susceptibilities to lymphocyte-mediated inhibition of intracellular growth. However, mice infected with the ΔsigF mutant showed a median time to death of 246 days compared with 161 days for wild-type strain-infected animals (P < 0.001). These data indicate that M. tuberculosis sigF is a nonessential alternate sigma factor both in axenic culture and for survival in macrophages in vitro. While the ΔsigF mutant produces a lethal infection of mice, it is less virulent than its wild-type counterpart by time-to-death analysis.

scholarly journals The l-Isoaspartyl Protein Repair Methyltransferase Enhances Survival of Aging Escherichia coli Subjected to Secondary Environmental Stresses

1998 ◽  
Vol 180 (10) ◽  
pp. 2623-2629 ◽  
Author(s):  
Jonathan E. Visick ◽  
Hui Cai ◽  
Steven Clarke
Keyword(s):  
Escherichia Coli ◽  
Stationary Phase ◽  
Protein Denaturation ◽  
Environmental Stresses ◽  
Protein Repair ◽  
Repeated Heating ◽  
E Coli ◽  
Competitive Disadvantage ◽  
Biological World

ABSTRACT Like its homologs throughout the biological world, thel-isoaspartyl protein repair methyltransferase ofEscherichia coli, encoded by the pcm gene, can convert abnormal l-isoaspartyl residues in proteins (which form spontaneously from asparaginyl or aspartyl residues) to normal aspartyl residues. Mutations in pcm were reported to greatly reduce survival in stationary phase and when cells were subjected to heat or osmotic stresses (C. Li and S. Clarke, Proc. Natl. Acad. Sci. USA 89:9885–9889, 1992). However, we subsequently demonstrated that those strains had a secondary mutation inrpoS, which encodes a stationary-phase-specific sigma factor (J. E. Visick and S. Clarke, J. Bacteriol. 179:4158–4163, 1997). We now show that the rpoS mutation, resulting in a 90% decrease in HPII catalase activity, can account for the previously observed phenotypes. We further demonstrate that a new pcmmutant lacks these phenotypes. Interestingly, the newly constructedpcm mutant, when maintained in stationary phase for extended periods, is susceptible to environmental stresses, including exposure to methanol, oxygen radical generation by paraquat, high salt concentrations, and repeated heating to 42°C. The pcmmutation also results in a competitive disadvantage in stationary-phase cells. All of these phenotypes can be complemented by a functionalpcm gene integrated elsewhere in the chromosome. These data suggest that protein denaturation and isoaspartyl formation may act synergistically to the detriment of aging E. coli and that the repair methyltransferase can play a role in limiting the accumulation of the potentially disruptive isoaspartyl residues in vivo.

scholarly journals Quorum-Sensing System and Stationary-Phase Sigma Factor (rpoS) of the Onion Pathogen Burkholderia cepacia Genomovar I Type Strain, ATCC 25416

2003 ◽  
Vol 69 (3) ◽  
pp. 1739-1747 ◽  
Author(s):  
Claudio Aguilar ◽  
Iris Bertani ◽  
Vittorio Venturi
Keyword(s):  
Quorum Sensing ◽  
Stationary Phase ◽  
Sigma Factor ◽  
Burkholderia Cepacia ◽  
Type Strain ◽  
Plant Pathogens ◽  
Signal Molecules ◽  
Strain Atcc ◽  
Sensing System ◽  
Quorum Sensing System

ABSTRACT Bacterial strains belonging to Burkholderia cepacia can be human opportunistic pathogens, plant pathogens, and plant growth promoting and have remarkable catabolic activity. B. cepacia consists of several genomovars comprising what is now known as the B. cepacia complex. Here we report the quorum-sensing system of a genomovar I onion rot type strain ATCC 25416. Quorum sensing is a cell-density-dependent regulatory response which involves the production of N-acyl homoserine lactone (HSL) signal molecules. The cep locus has been inactivated in the chromosome, and it has been shown that CepI is responsible for the biosynthesis of an N-hexanoyl HSL (C6-HSL) and an N-octanoyl HSL (C8-HSL) and that the cep locus regulates protease production as well as onion pathogenicity via the expression of a secreted polygalacturonase. A cep-lacZ-based sensor plasmid has been constructed and used to demonstrate that CepR responded to C6-HSL with only 15% of the molar efficiency of C8-HSL, that a cepR knockout mutant synthesized 70% less HSLs, and that CepR responded best towards long-chain HSLs. In addition, we also report the cloning and characterization of the stationary-phase sigma factor gene rpoS of B. cepacia ATCC 25416. It was established that quorum sensing in B. cepacia has a negative effect on rpoS expression as determined by using an rpoS-lacZ transcriptional fusion; on the other hand, rpoS-null mutants displayed no difference in the accumulation of HSL signal molecules.

scholarly journals Coordinated Hibernation of Transcriptional and Translational Apparatus during Growth Transition ofEscherichia colito Stationary Phase

mSystems ◽  
2018 ◽  
Vol 3 (5) ◽  
Author(s):  
Hideji Yoshida ◽  
Tomohiro Shimada ◽  
Akira Ishihama
Keyword(s):  
Stationary Phase ◽  
Sigma Factor ◽  
Exponential Phase ◽  
Screening System ◽  
Content Type ◽  
Genome Expression ◽  
70S Ribosome ◽  
K 12 ◽  
Sigma Subunit ◽  
Translational Apparatus

ABSTRACTIn the process ofEscherichia coliK-12 growth from exponential phase to stationary, marked alteration takes place in the pattern of overall genome expression through modulation of both parts of the transcriptional and translational apparatus. In transcription, the sigma subunit with promoter recognition properties is replaced from the growth-related factor RpoD by the stationary-phase-specific factor RpoS. The unused RpoD is stored by binding with the anti-sigma factor Rsd. In translation, the functional 70S ribosome is converted to inactive 100S dimers through binding with the ribosome modulation factor (RMF). Up to the present time, the regulatory mechanisms of expression of these two critical proteins, Rsd and RMF, have remained totally unsolved. In this study, attempts were made to identify the whole set of transcription factors involved in transcription regulation of thersdandrmfgenes using the newly developed promoter-specific transcription factor (PS-TF) screening system. In the first screening, 74 candidate TFs with binding activity to both of thersdandrmfpromoters were selected from a total of 194 purified TFs. After 6 cycles of screening, we selected 5 stress response TFs, ArcA, McbR, RcdA, SdiA, and SlyA, for detailed analysisin vitroandin vivoof their regulatory roles. Results indicated that bothrsdandrmfpromoters are repressed by ArcA and activated by McbR, RcdA, SdiA, and SlyA. We propose the involvement of a number of TFs in simultaneous and coordinated regulation of the transcriptional and translational apparatus. By using genomic SELEX (gSELEX) screening, each of the five TFs was found to regulate not only thersdandrmfgenes but also a variety of genes for growth and survival.IMPORTANCEDuring the growth transition ofE. colifrom exponential phase to stationary, the genome expression pattern is altered markedly. For this alteration, the transcription apparatus is altered by binding of anti-sigma factor Rsd to the RpoD sigma factor for sigma factor replacement, while the translation machinery is modulated by binding of RMF to 70S ribosome to form inactive ribosome dimer. Using the PS-TF screening system, a number of TFs were found to bind to both thersdandrmfpromoters, of which the regulatory roles of 5 representative TFs (one repressor ArcA and the four activators McbR, RcdA, SdiA, and SlyA) were analyzed in detail. The results altogether indicated the involvement of a common set of TFs, each sensing a specific environmental condition, in coordinated hibernation of the transcriptional and translational apparatus for adaptation and survival under stress conditions.

scholarly journals RpoS-Dependent Transcriptional Control ofsprE: Regulatory Feedback Loop

2001 ◽  
Vol 183 (20) ◽  
pp. 5974-5981 ◽  
Author(s):  
Natividad Ruiz ◽  
Celeste N. Peterson ◽  
Thomas J. Silhavy
Keyword(s):  
Escherichia Coli ◽  
Stationary Phase ◽  
Intergenic Region ◽  
Feedback Loop ◽  
Transcriptional Control ◽  
Response Regulator ◽  
Phase Response ◽  
Specific Regulation ◽  
Regulatory Feedback Loop

ABSTRACT The stationary-phase response exhibited by Escherichia coli upon nutrient starvation is mainly induced by a decrease of the ClpXP-dependent degradation of the alternate primary ς factor RpoS. Although it is known that the specific regulation of this proteolysis is exercised by the orphan response regulator SprE, it remains unclear how SprE's activity is regulated in vivo. Previous studies have demonstrated that the cellular content of SprE itself is paradoxically increased in stationary-phase cells in an RpoS-dependent fashion. We show here that this RpoS-dependent upregulation of SprE levels is due to increased transcription. Furthermore, we demonstrate that sprE is part of the two-generssA-sprE operon, but it can also be transcribed from an additional RpoS-dependent promoter located in therssA-sprE intergenic region. In addition, by using an in-frame deletion in rssA we found that RssA does not regulate either SprE or RpoS under the conditions tested.

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