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Vogt SL, Raivio TL. Just scratching the surface: an expanding view of the Cpx envelope stress response. FEMS Microbiol Lett 2011; 326:2-11. [DOI: 10.1111/j.1574-6968.2011.02406.x] [Citation(s) in RCA: 145] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Revised: 08/17/2011] [Accepted: 08/22/2011] [Indexed: 11/28/2022] Open
Affiliation(s)
- Stefanie L. Vogt
- Department of Biological Sciences; University of Alberta; Edmonton; AB; Canada
| | - Tracy L. Raivio
- Department of Biological Sciences; University of Alberta; Edmonton; AB; Canada
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2
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May T, Ito A, Okabe S. Characterization and global gene expression of F− phenocopies during Escherichia coli biofilm formation. Mol Genet Genomics 2010; 284:333-42. [DOI: 10.1007/s00438-010-0571-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2010] [Accepted: 08/15/2010] [Indexed: 10/19/2022]
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3
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Zahrl D, Wagner M, Bischof K, Koraimann G. Expression and assembly of a functional type IV secretion system elicit extracytoplasmic and cytoplasmic stress responses in Escherichia coli. J Bacteriol 2006; 188:6611-21. [PMID: 16952953 PMCID: PMC1595493 DOI: 10.1128/jb.00632-06] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Conditions perturbing protein homeostasis are known to induce cellular stress responses in prokaryotes and eukaryotes. Here we show for the first time that expression and assembly of a functional type IV secretion (T4S) machinery elicit extracytoplasmic and cytoplasmic stress responses in Escherichia coli. After induction of T4S genes by a nutritional upshift and assembly of functional DNA transporters encoded by plasmid R1-16, host cells activated the CpxAR envelope stress signaling system, as revealed by induction or repression of downstream targets of the CpxR response regulator. Furthermore, we observed elevated transcript levels of cytoplasmic stress genes, such as groESL, with a concomitant increase of sigma(32) protein levels in cells expressing T4S genes. A traA null mutant of plasmid R1-16, which lacks the functional gene encoding the major pilus protein pilin, showed distinctly reduced stress responses. These results corroborated our conclusion that the activation of bacterial stress networks was dependent on the presence of functional T4S machinery. Additionally, we detected increased transcription from the rpoHp(1) promoter in the presence of an active T4S system. Stimulation of rpoHp(1) was dependent on the presence of CpxR, suggesting a hitherto undocumented link between CpxAR and sigma(32)-regulated stress networks.
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MESH Headings
- Adaptation, Physiological
- Bacterial Proteins
- Biological Transport
- Chaperonins/biosynthesis
- Conjugation, Genetic
- Escherichia coli/genetics
- Escherichia coli/metabolism
- Escherichia coli/physiology
- Escherichia coli Proteins/biosynthesis
- Escherichia coli Proteins/physiology
- Gene Expression Profiling
- Gene Expression Regulation, Bacterial
- Genes, Bacterial
- Heat-Shock Proteins/biosynthesis
- Heat-Shock Proteins/genetics
- Models, Biological
- Mutation
- Pili, Sex/genetics
- Pili, Sex/metabolism
- Plasmids/genetics
- Protein Kinases/physiology
- RNA, Bacterial/analysis
- RNA, Messenger/analysis
- Regulon/physiology
- Sigma Factor/biosynthesis
- Sigma Factor/genetics
- Transcription, Genetic
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Affiliation(s)
- Doris Zahrl
- Institut für Molekulare Biowissenschaften (IMB), Karl-Franzens-Universität Graz, Universitätsplatz 2, A-8010 Graz, Austria
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4
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Dorel C, Lejeune P, Rodrigue A. The Cpx system of Escherichia coli, a strategic signaling pathway for confronting adverse conditions and for settling biofilm communities? Res Microbiol 2006; 157:306-14. [PMID: 16487683 DOI: 10.1016/j.resmic.2005.12.003] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2005] [Revised: 12/22/2005] [Accepted: 12/22/2005] [Indexed: 01/15/2023]
Abstract
Amongst the thirty or so two-component systems known in Escherichia coli, the Cpx system has been described as being a stress response system the main function of which is to respond to damage to the cell envelope via activation of proteases and folding catalysts. Nevertheless, the size of the Cpx regulon (several dozens of target genes) and the diversity of the physiological functions associated with it (resistance to hostile conditions, mobility, adherence factors, metabolism, etc.) indicate that the role of Cpx in cell physiology is undoubtedly more complex. The range of cellular functions affected by activation of the Cpx pathway corresponds quite closely to the description of the physiological state of cells grown in biofilms. We suggest that Cpx is a strategic signaling pathway for facing adverse conditions and for settling biofilm communities. Current knowledge of the regulatory mechanisms of the CpxR response (transcriptional and post-transcriptional) and the interactions between CpxR and the other bacterial regulatory systems are presented.
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Affiliation(s)
- Corinne Dorel
- Unité de Microbiologie et Génétique Composante INSA, UMR CNRS 5122, Université Claude Bernard Lyon I, 10 rue Dubois, 69 622 Villeurbanne cedex, France.
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5
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Camacho EM, Serna A, Madrid C, Marqués S, Fernández R, de la Cruz F, Juárez A, Casadesús J. Regulation of finP transcription by DNA adenine methylation in the virulence plasmid of Salmonella enterica. J Bacteriol 2005; 187:5691-9. [PMID: 16077115 PMCID: PMC1196074 DOI: 10.1128/jb.187.16.5691-5699.2005] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2005] [Accepted: 05/16/2005] [Indexed: 11/20/2022] Open
Abstract
DNA adenine methylase (Dam(-)) mutants of Salmonella enterica serovar Typhimurium contain reduced levels of FinP RNA encoded on the virulence plasmid. Dam methylation appears to regulate finP transcription, rather than FinP RNA stability or turnover. The finP promoter includes canonical -10 and -35 modules and depends on the sigma(70) factor. Regulation of finP transcription by Dam methylation does not require DNA sequences upstream from the -35 module, indicating that Dam acts at the promoter itself or downstream. Unexpectedly, a GATC site overlapping with the -10 module is likewise dispensable for Dam-mediated regulation. These observations indicate that Dam methylation regulates finP transcription indirectly and suggest the involvement of a host factor(s) responsive to the Dam methylation state of the cell. We provide evidence that one such factor is the nucleoid protein H-NS, which acts as a repressor of finP transcription in a Dam(-) background. H-NS also restrains transcription of the overlapping traJ gene, albeit in a Dam-independent fashion. Hence, the decreased FinP RNA content found in Dam(-) hosts of S. enterica appears to result from H-NS-mediated repression of finP transcription.
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Affiliation(s)
- Eva M Camacho
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Apartado 1095, E-41080 Sevilla, Spain
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6
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Nevesinjac AZ, Raivio TL. The Cpx envelope stress response affects expression of the type IV bundle-forming pili of enteropathogenic Escherichia coli. J Bacteriol 2005; 187:672-86. [PMID: 15629938 PMCID: PMC543543 DOI: 10.1128/jb.187.2.672-686.2005] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The Cpx envelope stress response mediates adaptation to potentially lethal envelope stresses in Escherichia coli. The two-component regulatory system consisting of the sensor kinase CpxA and the response regulator CpxR senses and mediates adaptation to envelope insults believed to result in protein misfolding in this compartment. Recently, a role was demonstrated for the Cpx response in the biogenesis of P pili, attachment organelles expressed by uropathogenic E. coli. CpxA senses misfolded P pilus assembly intermediates and initiates increased expression of both assembly and regulatory factors required for P pilus elaboration. In this report, we demonstrate that the Cpx response is also involved in the expression of the type IV bundle-forming pili of enteropathogenic E. coli (EPEC). Bundle-forming pili were not elaborated from an exogenous promoter in E. coli laboratory strain MC4100 unless the Cpx pathway was constitutively activated. Further, an EPEC cpxR mutant synthesized diminished levels of bundle-forming pili and was significantly affected in adherence to epithelial cells. Since type IV bundle-forming pili are very different from chaperone-usher-type P pili in both form and biogenesis, our results suggest that the Cpx envelope stress response plays a general role in the expression of envelope-localized organelles with diverse structures and assembly pathways.
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Affiliation(s)
- Anna Z Nevesinjac
- Department of Biological Sciences, CW405A Biological Sciences Building, University of Alberta, Edmonton, Alberta, Canada T6G 2E9
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7
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Starcic-Erjavec M, van Putten JPM, Gaastra W, Jordi BJAM, Grabnar M, Zgur-Bertok D. H-NS and Lrp serve as positive modulators of traJ expression from the Escherichia coli plasmid pRK100. Mol Genet Genomics 2003; 270:94-102. [PMID: 12942368 DOI: 10.1007/s00438-003-0908-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2003] [Accepted: 07/18/2003] [Indexed: 11/26/2022]
Abstract
Conjugative transfer of F-like plasmids is a tightly regulated process. The TraJ protein is the main positive activator of the tra operon which encodes products required for conjugative transfer of F-like plasmids. Nucleotide sequence analysis revealed potential Lrp and H-NS binding sites in the traJ regulatory region. Expression of a traJ-lacZ fusion in hns and lrp mutant strains showed that both are positive modulators of traJ expression. Competitive RT-PCR demonstrated that H-NS and Lrp exert their effect at the transcriptional level. Electrophoretic mobility-shift assays showed that H-NS and Lrp proteins bind to the traJ promoter. Conjugative transfer of pRK100 was decreased in hns but not in lrp mutant strains. Together, the results indicate H-NS and Lrp function as activators of traJ transcription.
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Affiliation(s)
- M Starcic-Erjavec
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Vecna pot 111, 1000 Ljubljana, Slovenia
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8
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Starcic M, Zgur-Bertok D, Jordi BJAM, Wösten MMSM, Gaastra W, van Putten JPM. The cyclic AMP-cyclic AMP receptor protein complex regulates activity of the traJ promoter of the Escherichia coli conjugative plasmid pRK100. J Bacteriol 2003; 185:1616-23. [PMID: 12591879 PMCID: PMC148056 DOI: 10.1128/jb.185.5.1616-1623.2003] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The TraJ protein is a central activator of F-like plasmid conjugal transfer. In a search for regulators of traJ expression, we studied the possible regulatory role of the cyclic AMP (cAMP)-cAMP receptor protein (CRP) complex in traJ transcription using a traJ-lacZ reporter system. A comparison of the enzyme activities in the wild-type Escherichia coli strain MC4100 with those in cya and crp mutants indicated that disruption of the formation of the cAMP-CRP complex negatively influenced the activity of the traJ promoter of the F-like plasmid pRK100. The defect in the cya mutant was partially restored by addition of exogenous cAMP. Competitive reverse transcription-PCR performed with RNA isolated from the wild-type and mutant strains showed that the cAMP-CRP complex exerted its effect at the level of transcription. Electrophoretic mobility shift assays with purified CRP demonstrated that there was direct binding of CRP to the traJ promoter region. DNase I footprint experiments mapped the CRP binding site around position -67.5 upstream of the putative traJ promoter. Targeted mutagenesis of the traJ promoter region confirmed the location of the CRP binding site. Consistent with the demonstrated regulation of TraJ by the cAMP-CRP complex, mutants with defects in cya or crp exhibited reduced conjugal transfer from pRK100.
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Affiliation(s)
- Marjanca Starcic
- Department of Biology, University of Ljubljana, 1000 Ljubljana, Slovenia
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9
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Gubbins MJ, Lau I, Will WR, Manchak JM, Raivio TL, Frost LS. The positive regulator, TraJ, of the Escherichia coli F plasmid is unstable in a cpxA* background. J Bacteriol 2002; 184:5781-8. [PMID: 12270837 PMCID: PMC139618 DOI: 10.1128/jb.184.20.5781-5788.2002] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Cpx (conjugative plasmid expression) stress response of Escherichia coli is induced in response to extracytoplasmic signals generated in the cell envelope, such as misfolded proteins in the periplasm. Detection of stress is mediated by the membrane-bound histidine kinase, CpxA. Signaling of the response regulator CpxR by activated CpxA results in the expression of several factors required for responding to cell envelope stress. CpxA was originally thought to be required for the expression of the positive regulator of the F plasmid transfer (tra) operon, TraJ. It was later determined that constitutive gain-of-function mutations in cpxA led to activation of the Cpx envelope stress response and decreased TraJ expression. In order to determine the nature of the downregulation of TraJ, the level of expression of TraJ, TraM, and TraY, the F-encoded regulatory proteins of the F tra region, was determined both in a cpxA* background and in a wild-type background in which the Cpx stress response was induced by overexpression of the outer membrane lipoprotein, NlpE. Our results suggest that TraJ downregulation is controlled by a posttranscriptional mechanism that operates in the cytoplasm in response to upregulation of the Cpx stress response by both the cpxA* gain-of-function mutation and the overexpression of NlpE.
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Affiliation(s)
- Michael J Gubbins
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada T6G 2E9
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10
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De Wulf P, Lin EC. Cpx two-component signal transduction in Escherichia coli: excessive CpxR-P levels underlie CpxA* phenotypes. J Bacteriol 2000; 182:1423-6. [PMID: 10671468 PMCID: PMC94433 DOI: 10.1128/jb.182.5.1423-1426.2000] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Escherichia coli, the CpxA-CpxR two-component signal transduction system and the sigma(E) and sigma(32) response pathways jointly regulate gene expression in adaptation to adverse conditions. These include envelope protein distress, heat shock, oxidative stress, high pH, and entry into stationary phase. Certain mutant versions of the CpxA sensor protein (CpxA* proteins) exhibit an elevated ratio of kinase to phosphatase activity on CpxR, the cognate response regulator. As a result, CpxA* strains display numerous phenotypes, many of which cannot be easily related to currently known functions of the CpxA-CpxR pathway. It is unclear whether CpxA* phenotypes are caused solely by hyperphosphorylation of CpxR. We here report that all of the tested CpxA* phenotypes depend on elevated levels of CpxR-P and not on cross-signalling of CpxA* to noncognate response regulators.
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Affiliation(s)
- P De Wulf
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA
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11
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De Wulf P, Kwon O, Lin EC. The CpxRA signal transduction system of Escherichia coli: growth-related autoactivation and control of unanticipated target operons. J Bacteriol 1999; 181:6772-8. [PMID: 10542180 PMCID: PMC94143 DOI: 10.1128/jb.181.21.6772-6778.1999] [Citation(s) in RCA: 120] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Escherichia coli, the CpxRA two-component signal transduction system senses and responds to aggregated and misfolded proteins in the bacterial envelope. We show that CpxR-P (the phosphorylated form of the cognate response regulator) activates cpxRA expression in conjunction with RpoS, suggesting an involvement of the Cpx system in stationary-phase survival. Engagement of the CpxRA system in functions beyond protein management is indicated by several putative targets identified after a genomic screening for the CpxR-P recognition consensus sequence. Direct negative control of the newly identified targets motABcheAW (specifying motility and chemotaxis) and tsr (encoding the serine chemoreceptor) by CpxR-P was shown by electrophoretic mobility shift analysis and Northern hybridization. The results suggest that the CpxRA system plays a core role in an extensive stress response network in which the coordination of protein turnover and energy conservation may be the unifying element.
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Affiliation(s)
- P De Wulf
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA
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12
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Abstract
This map is an update of the edition 9 map by Berlyn et al. (M. K. B. Berlyn, K. B. Low, and K. E. Rudd, p. 1715-1902, in F. C. Neidhardt et al., ed., Escherichia coli and Salmonella: cellular and molecular biology, 2nd ed., vol. 2, 1996). It uses coordinates established by the completed sequence, expressed as 100 minutes for the entire circular map, and adds new genes discovered and established since 1996 and eliminates those shown to correspond to other known genes. The latter are included as synonyms. An alphabetical list of genes showing map location, synonyms, the protein or RNA product of the gene, phenotypes of mutants, and reference citations is provided. In addition to genes known to correspond to gene sequences, other genes, often older, that are described by phenotype and older mapping techniques and that have not been correlated with sequences are included.
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Affiliation(s)
- M K Berlyn
- Department of Biology and School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut 06520-8104, USA.
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13
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Abstract
We have examined the effect of the F plasmid TraY protein on tra gene expression in vivo. Expression was assayed as alkaline phosphatase activity in cells containing a traY phi(traA'-'phoA)hyb operon under traY promoter control. Amber mutations in traY significantly reduced alkaline phosphatase activity. Since nonsense polarity effects were minimal, if they occurred at all, these data provide the first direct evidence that TraY regulates tra gene expression.
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Affiliation(s)
- P M Silverman
- Program in Molecular and Cell Biology, Oklahoma Medical Research Foundation, Oklahoma City 73104, USA.
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14
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Danese PN, Snyder WB, Cosma CL, Davis LJ, Silhavy TJ. The Cpx two-component signal transduction pathway of Escherichia coli regulates transcription of the gene specifying the stress-inducible periplasmic protease, DegP. Genes Dev 1995; 9:387-98. [PMID: 7883164 DOI: 10.1101/gad.9.4.387] [Citation(s) in RCA: 269] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
DegP is a heat-shock inducible periplasmic protease in Escherichia coli. Unlike the cytoplasmic heat shock proteins, DegP is not transcriptionally regulated by the classical heat shock regulon coordinated by sigma 32. Rather, the degP gene is transcriptionally regulated by an alternate heat shock sigma factor, sigma E. Previous studies have demonstrated a signal transduction pathway that monitors the amount of outer-membrane proteins in the bacterial envelope and modulates degP levels in response to this extracytoplasmic parameter. To analyze the transcriptional regulation of degP, we examined mutations that altered transcription of a degP-lacZ operon fusion. Gain-of-function mutations in cpxA, which specifies a two-component sensor protein, stimulate transcription from degP. Defined null mutations in cpxA or the gene encoding its cognate response regulator, cpxR, decrease transcription from degP. These null mutations also prevent transcriptional induction of degP in response to overexpression of a gene specifying an envelope lipoprotein. Cpx-mediated transcription of degP is partially dependent on the activity of E sigma E, suggesting that the Cpx pathway functions in concert with E sigma E and perhaps other RNA polymerases to drive transcription of degP.
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Affiliation(s)
- P N Danese
- Department of Molecular Biology, Princeton University, New Jersey 08544
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15
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Dempsey WB. traJ sense RNA initiates at two different promoters in R100-1 and forms two stable hybrids with antisense finP RNA. Mol Microbiol 1994; 13:313-26. [PMID: 7527120 DOI: 10.1111/j.1365-2958.1994.tb00425.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
RNase protection experiments show that the sizes of the two R100 finP molecules are 74 and 135 nucleotides. In an RNase III mutant, finP transcripts form stable double-stranded hybrids of 108 bp and 68 bp with traJ transcripts. RNase protection experiments also show that most R100-1 transcripts originating in traM cross the traM-traJ intergenic region and end inside the untranslated leader region of traJ. Some extend into the traJ open reading frame. These findings mean that the antisense finP RNA, thought to regulate traJ translation, must regulate traJ transcripts from both J and M promoters.
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Affiliation(s)
- W B Dempsey
- Veterans' Affairs Medical Center, Dallas, Texas
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Gaudin HM, Silverman PM. Contributions of promoter context and structure to regulated expression of the F plasmid traY promoter in Escherichia coli K-12. Mol Microbiol 1993; 8:335-42. [PMID: 8316084 DOI: 10.1111/j.1365-2958.1993.tb01577.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Expression of the F plasmid traY promoter in vivo requires both host (E. coli) and plasmid encoded proteins. As judged by transcript size and primer extension analyses, the F plasmid traY promoter was utilized in vitro by purified E. coli sigma 70 RNA polymerase in the absence of other proteins. However, in vitro transcription required supercoiled templates. Endonuclease protection experiments showed that RNA polymerase is unable to form a stable complex at the traY promoter in linear or relaxed circular templates. In vitro transcription with linear templates could be elicited by altering the traY -10 and -35 hexamers to the consensus sequences. Alterations that reduced the effect of template supercoiling on apparent promoter strength in vitro also reduced the effect of the F plasmid TraJ protein on traY expression in vivo. Apparent traY promoter strength in vitro, estimated in template competition experiments, was unaltered by deletion of tra DNA normally upstream of the promoter, a change in promoter context that elicited high levels of promoter activity in TraJ- cells. These data suggest a model for regulated traY promoter activity in which a nucleoprotein complex involving tra DNA immediately upstream locally relaxes traY promoter DNA. TraJ and perhaps other activators could disrupt the complex, allowing promoter DNA to equilibrate at the prevailing negative superhelical density and thereby eliciting transcription initiation.
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Affiliation(s)
- H M Gaudin
- Program in Molecular and Cell Biology, Oklahoma Medical Research Foundation, Oklahoma 73104
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