Faculty Opinions recommendation of Mutant forms of the Azotobacter vinelandii transcriptional activator NifA resistant to inhibition by the NifL regulatory protein.

2003 ◽  
Author(s):  
Juan Luis Ramos
Keyword(s):  
Azotobacter Vinelandii ◽  
Regulatory Protein ◽  
Transcriptional Activator ◽  
Mutant Forms

scholarly journals Mutant Forms of the Azotobacter vinelandii Transcriptional Activator NifA Resistant to Inhibition by the NifL Regulatory Protein

2002 ◽  
Vol 184 (24) ◽  
pp. 6777-6785 ◽  
Author(s):  
Francisca Reyes-Ramirez ◽  
Richard Little ◽  
Ray Dixon
Keyword(s):  
Azotobacter Vinelandii ◽  
Regulatory Protein ◽  
Transcriptional Activator ◽  
Growth Conditions ◽  
Redox Status ◽  
Mutant Protein ◽  
Amino Terminal ◽  
Transcriptional Activator Protein

ABSTRACT The Azotobacter vinelandii σ54-dependent transcriptional activator protein NifA is regulated by the NifL protein in response to redox, carbon, and nitrogen status. Under conditions inappropriate for nitrogen fixation, NifL inhibits transcription activation by NifA through the formation of the NifL-NifA protein complex. NifL inhibits the ATPase activity of the central AAA+ domain of NifA required to drive open complex formation by σ54-RNA polymerase and may also inhibit the activator-polymerase interaction. To analyze the mechanism of inhibition in greater detail, we isolated NifA mutants which are resistant to the inhibitory action of NifL. Mutations in both the amino-terminal GAF domain and the catalytic AAA+ domain of NifA were isolated. Several mutants blocked inhibition by NifL in response to both nitrogen and redox status, whereas some of the mutant NifA proteins were apparently able to discriminate between the forms of NifL present under different environmental conditions. One mutant protein, NifA-Y254N, was resistant to NifL under conditions of anaerobic nitrogen excess but was relatively sensitive to NifL under aerobic growth conditions. The properties of the purified mutant protein in vitro were consistent with the in vivo phenotype and indicate that NifA-Y254N is not responsive to the nitrogen signal conveyed by the interaction of NifL with A. vinelandii GlnK but is responsive to the oxidized form of NifL when ADP is present. Our observations suggest that different conformers of NifL may be generated in response to discrete signal transduction events and that both the GAF and AAA+ domains of NifA are involved in the response to NifL.

Posttranscriptional regulation of PhbR, the transcriptional activator of polyhydroxybutyrate synthesis, by iron and the sRNA ArrF in Azotobacter vinelandii

2013 ◽  
Vol 98 (5) ◽  
pp. 2173-2182 ◽  
Author(s):  
Luis Felipe Muriel-Millán ◽  
Mildred Castellanos ◽  
Jose Alberto Hernandez-Eligio ◽  
Soledad Moreno ◽  
Guadalupe Espín
Keyword(s):  
Posttranscriptional Regulation ◽  
Azotobacter Vinelandii ◽  
Transcriptional Activator

scholarly journals Glucose repression of the yeast ADH2 gene occurs through multiple mechanisms, including control of the protein synthesis of its transcriptional activator, ADR1.

1992 ◽  
Vol 12 (4) ◽  
pp. 1663-1673 ◽  
Author(s):  
R C Vallari ◽  
W J Cook ◽  
D C Audino ◽  
M J Morgan ◽  
D E Jensen ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Glucose Repression ◽  
Regulatory Protein ◽  
Transcriptional Activator ◽  
Protein Translation ◽  
Growth Conditions ◽  
Mrna Levels ◽  
Coding Region ◽  
Glucose Depletion

The rate of ADH2 transcription increases dramatically when Saccharomyces cerevisiae cells are shifted from glucose to ethanol growth conditions. Since ADH2 expression under glucose growth conditions is strictly dependent on the dosage of the transcriptional activator ADR1, we investigated the possibility that regulation of the rate of ADR1 protein synthesis plays a role in controlling ADR1 activation of ADH2 transcription. We found that the rate of ADR1 protein synthesis increased 10- to 16-fold within 40 to 60 min after glucose depletion, coterminous with initiation of ADH2 transcription. Changes in ADR1 mRNA levels contributed only a twofold effect on ADR1 protein synthetic differences. The 510-nt untranslated ADR1 mRNA leader sequence was found to have no involvement in regulating the rate of ADR1 protein synthesis. In contrast, sequences internal to ADR1 coding region were determined to be necessary for controlling ADR1 translation. The ADR1c mutations which enhance ADR1 activity under glucose growth conditions did not affect ADR1 protein translation. ADR1 was also shown to be multiply phosphorylated in vivo under both ethanol and glucose growth conditions. Our results indicate that derepression of ADH2 occurs through multiple mechanisms involving the ADR1 regulatory protein.

scholarly journals Analysis of the Functions of Herpes Simplex Virus Type 1 Regulatory Protein ICP0 That Are Critical for Lytic Infection and Derepression of Quiescent Viral Genomes

2009 ◽  
Vol 83 (10) ◽  
pp. 4963-4977 ◽  
Author(s):  
Roger D. Everett ◽  
Marie-Laure Parsy ◽  
Anne Orr
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Regulatory Protein ◽  
Lytic Infection ◽  
Viral Genomes ◽  
Protein Icp0 ◽  
Simplex Virus ◽  
Mutant Forms ◽  
Hsv 1

ABSTRACT Herpes simplex virus type 1 (HSV-1) immediate-early regulatory protein ICP0 is important for stimulating the initiation of the lytic cycle and efficient reactivation of latent or quiescent infection. Extensive investigation has suggested several potential functions for ICP0, including interference in the interferon response, disruption of functions connected with PML nuclear bodies (ND10), and inhibition of cellular histone deacetylase (HDAC) activity through an interaction with the HDAC-1 binding partner CoREST. Analysis of the significance of these potential functions and whether they are direct or indirect effects of ICP0 is complicated because HSV-1 mutants expressing mutant forms of ICP0 infect cells with widely differing efficiencies. On the other hand, transfection approaches for ICP0 expression do not allow studies of whole cell populations because of their limited efficiency. To overcome these problems, we have established a cell line in which ICP0 expression can be induced at levels pertaining during the early stages of HSV-1 infection in virtually all cells in the culture. Such cells enable 100% complementation of ICP0-null mutant HSV-1. Using cells expressing the wild type and a variety of mutant forms of ICP0, we have used this system to analyze the role of defined domains of the protein in stimulating lytic infection and derepression from quiescence. Activity in these core functions correlated well the ability of ICP0 to disrupt ND10 and inhibit the recruitment of ND10 proteins to sites closely associated with viral genomes at the onset of infection, whereas the CoREST binding region was neither sufficient nor necessary for ICP0 function in lytic and reactivating infections.

scholarly journals Anabaena sp. Strain PCC 7120 Gene devH Is Required for Synthesis of the Heterocyst Glycolipid Layer

2005 ◽  
Vol 187 (7) ◽  
pp. 2326-2331 ◽  
Author(s):  
Martha E. Ramírez ◽  
Pratibha B. Hebbar ◽  
Ruanbao Zhou ◽  
C. Peter Wolk ◽  
Stephanie E. Curtis
Keyword(s):  
Nitrogen Fixation ◽  
Nitrogenase Activity ◽  
Regulatory Protein ◽  
Protein A ◽  
Filamentous Cyanobacterium ◽  
Fixed Nitrogen ◽  
Ultrastructural Studies ◽  
Anabaena Sp ◽  
Pcc 7120 ◽  
Mutant Forms

ABSTRACT In response to deprivation for fixed nitrogen, the filamentous cyanobacterium Anabaena sp. strain PCC 7120 provides a microoxic intracellular environment for nitrogen fixation through the differentiation of semiregularly spaced vegetative cells into specialized cells called heterocysts. The devH gene is induced during heterocyst development and encodes a product with characteristics of a trans-acting regulatory protein. A devH mutant forms morphologically distinguishable heterocysts but is Fox−, incapable of nitrogen fixation in the presence of oxygen. We demonstrate that rearrangements of nitrogen fixation genes take place normally in the devH mutant and that it is Fix+, i.e., has nitrogenase activity under anoxic conditions. The Fox− phenotype was shown by ultrastructural studies to be associated with the absence of the glycolipid layer of the heterocyst envelope. The expression of glycolipid biosynthetic genes in the mutant is greatly reduced, and heterocyst glycolipids are undetectable.

The redox- and fixed nitrogen-responsive regulatory protein NIFL from Azotobacter vinelandii comprises discrete flavin and nucleotide-binding domains

2002 ◽  
Vol 28 (1) ◽  
pp. 179-192 ◽  
Author(s):  
Erik Söderbäck ◽  
Franscisca Reyes-Ramirez ◽  
Trevor Eydmann ◽  
Sara Austin ◽  
Susan Hill ◽  
...  
Keyword(s):  
Azotobacter Vinelandii ◽  
Regulatory Protein ◽  
Nucleotide Binding ◽  
Fixed Nitrogen ◽  
Binding Domains

scholarly journals Molecular Determinants for PspA-Mediated Repression of the AAA Transcriptional Activator PspF

2005 ◽  
Vol 187 (9) ◽  
pp. 3238-3248 ◽  
Author(s):  
Sarah Elderkin ◽  
Patricia Bordes ◽  
Susan Jones ◽  
Mathieu Rappas ◽  
Martin Buck
Keyword(s):  
Regulatory Protein ◽  
Membrane Integrity ◽  
Transcriptional Activator ◽  
Negative Regulator ◽  
E Coli ◽  
Molecular Determinants ◽  
Negative Effect

ABSTRACT The Escherichia coli phage shock protein system (pspABCDE operon and pspG gene) is induced by numerous stresses related to the membrane integrity state. Transcription of the psp genes requires the RNA polymerase containing the σ54 subunit and the AAA transcriptional activator PspF. PspF belongs to an atypical class of σ54 AAA activators in that it lacks an N-terminal regulatory domain and is instead negatively regulated by another regulatory protein, PspA. PspA therefore represses its own expression. The PspA protein is distributed between the cytoplasm and the inner membrane fraction. In addition to its transcriptional inhibitory role, PspA assists maintenance of the proton motive force and protein export. Several lines of in vitro evidence indicate that PspA-PspF interactions inhibit the ATPase activity of PspF, resulting in the inhibition of PspF-dependent gene expression. In this study, we characterize sequences within PspA and PspF crucial for the negative effect of PspA upon PspF. Using a protein fragmentation approach, we show that the integrity of the three putative N-terminal α-helical domains of PspA is crucial for the role of PspA as a negative regulator of PspF. A bacterial two-hybrid system allowed us to provide clear evidence for an interaction in E. coli between PspA and PspF in vivo, which strongly suggests that PspA-directed inhibition of PspF occurs via an inhibitory complex. Finally, we identify a single PspF residue that is a binding determinant for PspA.

scholarly journals RamA Is an Alternate Activator of the Multidrug Resistance Cascade in Enterobacter aerogenes

2004 ◽  
Vol 48 (7) ◽  
pp. 2518-2523 ◽  
Author(s):  
Renaud Chollet ◽  
Jacqueline Chevalier ◽  
Claude Bollet ◽  
Jean-Marie Pages ◽  
Anne Davin-Regli
Keyword(s):  
Escherichia Coli ◽  
Multidrug Resistance ◽  
Type Strain ◽  
Efflux Pump ◽  
Regulatory Protein ◽  
Enterobacter Aerogenes ◽  
Transcriptional Activator ◽  
Drug Efflux ◽  
Gene Encoding ◽  
Drug Efflux Pump

ABSTRACT Multidrug resistance (MDR) in Enterobacter aerogenes can be mediated by induction of MarA, which is triggered by certain antibiotics and phenolic compounds. In this study, we identified the gene encoding RamA, a 113-amino-acid regulatory protein belonging to the AraC-XylS transcriptional activator family, in the Enterobacter aerogenes ATCC 13048 type strain and in a clinical multiresistant isolate. Overexpression of RamA induced an MDR phenotype in drug-susceptible Escherichia coli JM109 and E. aerogenes ATCC 13048, as demonstrated by 2- to 16-fold-increased resistance to β-lactams, tetracycline, chloramphenicol, and quinolones, a decrease in porin production, and increased production of AcrA, a component of the AcrAB-TolC drug efflux pump. We show that RamA enhances the transcription of the marRAB operon but is also able to induce an MDR phenotype in a mar-deleted strain. We demonstrate here that RamA is a transcriptional activator of the Mar regulon and is also a self-governing activator of the MDR cascade.

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