aph(3′)-IIb, a Gene Encoding an
Aminoglycoside-Modifying Enzyme, Is under the Positive Control of
Surrogate Regulator
HpaA

ABSTRACT Pseudomonas aeruginosa harbors a chromosomal aminoglycoside phosphotransferase gene, aph(3′)-IIb, which confers P. aeruginosa resistance to several important aminoglycoside antibiotics, including kanamycin A and B, neomycin B and C, butirosin, and seldomycin F5. The aph(3′)-IIb gene has been found to be regulated by an AraC-type transcriptional regulator (HpaA) encoded by a gene located upstream of the aph(3′)-IIb gene. In the presence of 4-hydroxyphenylacetic acid (4-HPA), HpaA activates the expression of aph(3′)-IIb as well as that of the hpa regulon which encodes metabolic enzymes for the utilization of 4-HPA. hpaA and aph(3′)-IIb form an operon, and in response to the presence of 4-HPA, the wild-type P. aeruginosa strain PAK (but not its hpaA mutant strain) displays increased resistance to neomycin. A survey of 39 clinical and 19 environmental isolates of P. aeruginosa demonstrated in all of them the presence of an hpaA-aph gene cluster, while 56 out of the 58 isolates are able to utilize the 4-HPA as a sole carbon source, suggesting a feature common to P. aeruginosa strains. Interestingly, a larger portion of clinical isolates than environmental isolates showed 4-HPA-induced resistance to neomycin. The aph(3′)-IIb gene product is likely to function as a metabolic enzyme which has a cross-reactivity with aminoglycosides. These findings provide new insight into the possible mechanism of P. aeruginosa antibiotic resistance.

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Overproduction of SecA Suppresses the Export Defect Caused by a Mutation in the Gene Encoding the Escherichia coli Export Chaperone SecB

Journal of Bacteriology ◽

10.1128/jb.181.10.3010-3017.1999 ◽

1999 ◽

Vol 181 (10) ◽

pp. 3010-3017 ◽

Cited By ~ 5

Author(s):

Heather A. Cook ◽

Carol A. Kumamoto

Keyword(s):

Escherichia Coli ◽

Outer Membrane Proteins ◽

Protein A ◽

In Vivo Studies ◽

Wild Type ◽

Gene Encoding ◽

Precursor Proteins ◽

Additional Support ◽

Insight Into

ABSTRACT SecB is a cytosolic protein required for rapid and efficient export of particular periplasmic and outer membrane proteins inEscherichia coli. SecB promotes export by stabilizing newly synthesized precursor proteins in a nonnative conformation and by targeting the precursors to the inner membrane. Biochemical studies suggest that SecB facilitates precursor targeting by binding to the SecA protein, a component of the membrane-embedded translocation apparatus. To gain more insight into the functional interaction of SecB and SecA, in vivo, mutations in the secA locus that compensate for the export defect caused by the secBmissense mutation secBL75Q were isolated. Two suppressors were isolated, both of which led to the overproduction of wild-type SecA protein. In vivo studies demonstrated that the SecBL75Q mutant protein releases precursor proteins at a lower rate than does wild-type SecB. Increasing the level of SecA protein in the cell was found to reverse this slow-release defect, indicating that overproduction of SecA stimulates the turnover of SecBL75Q-precursor complexes. These findings lend additional support to the proposed pathway for precursor targeting in which SecB promotes targeting to the translocation apparatus by binding to the SecA protein.

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The γ-tubulin complex protein GCP6 is crucial for spindle morphogenesis but not essential for microtubule reorganization inArabidopsis

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1912240116 ◽

2019 ◽

Vol 116 (52) ◽

pp. 27115-27123 ◽

Cited By ~ 1

Author(s):

Huiying Miao ◽

Rongfang Guo ◽

Junlin Chen ◽

Qiaomei Wang ◽

Yuh-Ru Julie Lee ◽

...

Keyword(s):

Arabidopsis Thaliana ◽

Vegetative Growth ◽

Functional Form ◽

Plant Cells ◽

Wild Type ◽

Gene Encoding ◽

Small Complex ◽

Complex Protein ◽

Ring Complex ◽

Insight Into

γ-Tubulin typically forms a ring-shaped complex with 5 related γ-tubulin complex proteins (GCP2 to GCP6), and this γ-tubulin ring complex (γTuRC) serves as a template for microtubule (MT) nucleation in plants and animals. While the γTuRC takes part in MT nucleation in most eukaryotes, in fungi such events take place robustly with just the γ-tubulin small complex (γTuSC) assembled by γ-tubulin plus GCP2 and GCP3. To explore whether the γTuRC is the sole functional γ-tubulin complex in plants, we generated 2 mutants of theGCP6gene encoding the largest subunit of the γTuRC inArabidopsis thaliana. Both mutants showed similar phenotypes of dwarfed vegetative growth and reduced fertility. Thegcp6mutant assembled the γTuSC, while the wild-type cells had GCP6 join other GCPs to produce the γTuRC. Although thegcp6cells had greatly diminished γ-tubulin localization on spindle MTs, the protein was still detected there. Thegcp6cells formed spindles that lacked MT convergence and discernable poles; however, they managed to cope with the challenge of MT disorganization and were able to complete mitosis and cytokinesis. Our results reveal that the γTuRC is not the only functional form of the γ-tubulin complex for MT nucleation in plant cells, and that γ-tubulin-dependent, but γTuRC-independent, mechanisms meet the basal need of MT nucleation. Moreover, we show that the γTuRC function is more critical for the assembly of spindle MT array than for the phragmoplast. Thus, our findings provide insight into acentrosomal MT nucleation and organization.

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Transcriptional Regulation of Amino Acid Transport in Glioblastoma Multiforme

Cancers ◽

10.3390/cancers13246169 ◽

2021 ◽

Vol 13 (24) ◽

pp. 6169

Author(s):

Robyn A. Umans ◽

Joelle Martin ◽

Megan E. Harrigan ◽

Dipan C. Patel ◽

Lata Chaunsali ◽

...

Keyword(s):

Glioblastoma Multiforme ◽

Chromatin Immunoprecipitation ◽

Glutamate Release ◽

Transcriptional Regulator ◽

Mutant P53 ◽

Acid Transport ◽

Wild Type ◽

Gene Encoding ◽

P53 Expression ◽

Transcript Levels

Glioblastoma multiforme (GBM) is a deadly brain tumor with a large unmet therapeutic need. Here, we tested the hypothesis that wild-type p53 is a negative transcriptional regulator of SLC7A11, the gene encoding the System xc- (SXC) catalytic subunit, xCT, in GBM. We demonstrate that xCT expression is inversely correlated with p53 expression in patient tissue. Using representative patient derived (PDX) tumor xenolines with wild-type, null, and mutant p53 we show that p53 expression negatively correlates with xCT expression. Using chromatin immunoprecipitation studies, we present a molecular interaction whereby p53 binds to the SLC7A11 promoter, suppressing gene expression in PDX GBM cells. Accordingly, genetic knockdown of p53 increases SLC7A11 transcript levels; conversely, over-expressing p53 in p53-null GBM cells downregulates xCT expression and glutamate release. Proof of principal studies in mice with flank gliomas demonstrate that daily treatment with the mutant p53 reactivator, PRIMA-1Met, results in reduced tumor growth associated with reduced xCT expression. These findings suggest that p53 is a molecular switch for GBM glutamate biology, with potential therapeutic utility.

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Effects of an Autoregulatory Senescence-inhibitor Gene Construct on Nicotiana alata Link and Otto.

HortScience ◽

10.21273/hortsci.33.3.519d ◽

1998 ◽

Vol 33 (3) ◽

pp. 519d-519 ◽

Cited By ~ 4

Author(s):

Kenneth R. Schroeder ◽

Dennis P. Stimart

Keyword(s):

Agrobacterium Tumefaciens ◽

Plant Height ◽

Dry Weight ◽

Nicotiana Alata ◽

Wild Type ◽

Gene Encoding ◽

Delayed Senescence ◽

Gene Construct ◽

Shoot Dry Weight ◽

Inhibitor System

Nicotiana alata Link and Otto. was transformed via Agrobacterium tumefaciens encoding a senescence-specific promoter SAG12 cloned from Arabidopsis thaliana fused to a Agrobacterium tumefaciens gene encoding isopentenyl transferase (IPT) that catalyzes cytokinin synthesis. This was considered an autoregulatory senescence-inhibitor system. In 1996, we reported delayed senescence of intact flowers by 2 to 6 d and delayed leaf senescence of transgenic vs. wild-type N. alata. Further evaluations in 1997 revealed several other interesting effects of the SAG12-IPT gene construct. Measurement of chlorophyll content of mature leaves showed higher levels of both chlorophyll a and b in transgenic material under normal fertilization and truncated fertilization regimes. At 4 to 5 months of age transgenic plants expressed differences in plant height, branching, and dry weight. Plant height was reduced by 3 to 13 cm; branch counts increased 2 to 3 fold; and shoot dry weight increased up to 11 g over wild-type N. alata. These observations indicate the system is not tightly autoregulated and may prove useful to the floriculture industry for producing compact and more floriferous plants.

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Salicylic Acid Accumulation Controlled by LSD1 Is Essential in Triggering Cell Death in Response to Abiotic Stress

Cells ◽

10.3390/cells10040962 ◽

2021 ◽

Vol 10 (4) ◽

pp. 962

Author(s):

Maciej Jerzy Bernacki ◽

Anna Rusaczonek ◽

Weronika Czarnocka ◽

Stanisław Karpiński

Keyword(s):

Cell Death ◽

Salicylic Acid ◽

Abiotic Stress ◽

Wild Type ◽

Pr Genes ◽

Genes Expression ◽

Salicylic Acid Accumulation ◽

Cell Death Phenotype ◽

Insight Into

Salicylic acid (SA) is well known hormonal molecule involved in cell death regulation. In response to a broad range of environmental factors (e.g., high light, UV, pathogens attack), plants accumulate SA, which participates in cell death induction and spread in some foliar cells. LESION SIMULATING DISEASE 1 (LSD1) is one of the best-known cell death regulators in Arabidopsis thaliana. The lsd1 mutant, lacking functional LSD1 protein, accumulates SA and is conditionally susceptible to many biotic and abiotic stresses. In order to get more insight into the role of LSD1-dependent regulation of SA accumulation during cell death, we crossed the lsd1 with the sid2 mutant, caring mutation in ISOCHORISMATE SYNTHASE 1(ICS1) gene and having deregulated SA synthesis, and with plants expressing the bacterial nahG gene and thus decomposing SA to catechol. In response to UV A+B irradiation, the lsd1 mutant exhibited clear cell death phenotype, which was reversed in lsd1/sid2 and lsd1/NahG plants. The expression of PR-genes and the H2O2 content in UV-treated lsd1 were significantly higher when compared with the wild type. In contrast, lsd1/sid2 and lsd1/NahG plants demonstrated comparability with the wild-type level of PR-genes expression and H2O2. Our results demonstrate that SA accumulation is crucial for triggering cell death in lsd1, while the reduction of excessive SA accumulation may lead to a greater tolerance toward abiotic stress.

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Expression and function of the cdgD gene, encoding a CHASE–PAS-DGC-EAL domain protein, in Azospirillum brasilense

Scientific Reports ◽

10.1038/s41598-020-80125-3 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

José Francisco Cruz-Pérez ◽

Roxana Lara-Oueilhe ◽

Cynthia Marcos-Jiménez ◽

Ricardo Cuatlayotl-Olarte ◽

María Luisa Xiqui-Vázquez ◽

...

Keyword(s):

Azospirillum Brasilense ◽

Type Strain ◽

Wild Type Strain ◽

Soil Conditions ◽

Wild Type ◽

Gene Encoding ◽

Wheat Roots ◽

Genes Encoding ◽

In The Wild ◽

Plant Growth Promoting

AbstractThe plant growth-promoting bacterium Azospirillum brasilense contains several genes encoding proteins involved in the biosynthesis and degradation of the second messenger cyclic-di-GMP, which may control key bacterial functions, such as biofilm formation and motility. Here, we analysed the function and expression of the cdgD gene, encoding a multidomain protein that includes GGDEF-EAL domains and CHASE and PAS domains. An insertional cdgD gene mutant was constructed, and analysis of biofilm and extracellular polymeric substance production, as well as the motility phenotype indicated that cdgD encoded a functional diguanylate protein. These results were correlated with a reduced overall cellular concentration of cyclic-di-GMP in the mutant over 48 h compared with that observed in the wild-type strain, which was recovered in the complemented strain. In addition, cdgD gene expression was measured in cells growing under planktonic or biofilm conditions, and differential expression was observed when KNO3 or NH4Cl was added to the minimal medium as a nitrogen source. The transcriptional fusion of the cdgD promoter with the gene encoding the autofluorescent mCherry protein indicated that the cdgD gene was expressed both under abiotic conditions and in association with wheat roots. Reduced colonization of wheat roots was observed for the mutant compared with the wild-type strain grown in the same soil conditions. The Azospirillum-plant association begins with the motility of the bacterium towards the plant rhizosphere followed by the adsorption and adherence of these bacteria to plant roots. Therefore, it is important to study the genes that contribute to this initial interaction of the bacterium with its host plant.

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Volatile Anesthetics Affect Nutrient Availability in Yeast

Genetics ◽

10.1093/genetics/161.2.563 ◽

2002 ◽

Vol 161 (2) ◽

pp. 563-574

Author(s):

Laura K Palmer ◽

Darren Wolfe ◽

Jessica L Keeley ◽

Ralph L Keil

Keyword(s):

Amino Acids ◽

Nutrient Availability ◽

Wild Type Strain ◽

Volatile Anesthetic ◽

Volatile Anesthetics ◽

Wild Type ◽

Anesthetic Exposure ◽

Sites Of Action ◽

Insight Into ◽

Lines Of Evidence

Abstract Volatile anesthetics affect all cells and tissues tested, but their mechanisms and sites of action remain unknown. To gain insight into the cellular activities of anesthetics, we have isolated genes that, when overexpressed, render Saccharomyces cerevisiae resistant to the volatile anesthetic isoflurane. One of these genes, WAK3/TAT1, encodes a permease that transports amino acids including leucine and tryptophan, for which our wild-type strain is auxotrophic. This suggests that availability of amino acids may play a key role in anesthetic response. Multiple lines of evidence support this proposal: (i) Deletion or overexpression of permeases that transport leucine and/or tryptophan alters anesthetic response; (ii) prototrophic strains are anesthetic resistant; (iii) altered concentrations of leucine and tryptophan in the medium affect anesthetic response; and (iv) uptake of leucine and tryptophan is inhibited during anesthetic exposure. Not all amino acids are critical for this response since we find that overexpression of the lysine permease does not affect anesthetic sensitivity. These findings are consistent with models in which anesthetics have a physiologically important effect on availability of specific amino acids by altering function of their permeases. In addition, we show that there is a relationship between nutrient availability and ubiquitin metabolism in this response.

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NMR and LC-MS-Based Metabolomics to Study Osmotic Stress in Lignan-Deficient Flax

Molecules ◽

10.3390/molecules26030767 ◽

2021 ◽

Vol 26 (3) ◽

pp. 767

Author(s):

Kamar Hamade ◽

Ophélie Fliniaux ◽

Jean-Xavier Fontaine ◽

Roland Molinié ◽

Elvis Otogo Nnang ◽

...

Keyword(s):

Stress Response ◽

Osmotic Stress ◽

Biosynthetic Pathway ◽

Potential Role ◽

Plant Secondary Metabolites ◽

Wild Type ◽

Osmotic Stress Response ◽

Transgenic Flax ◽

Insight Into

Lignans, phenolic plant secondary metabolites, are derived from the phenylpropanoid biosynthetic pathway. Although, being investigated for their health benefits in terms of antioxidant, antitumor, anti-inflammatory and antiviral properties, the role of these molecules in plants remains incompletely elucidated; a potential role in stress response mechanisms has been, however, proposed. In this study, a non-targeted metabolomic analysis of the roots, stems, and leaves of wild-type and PLR1-RNAi transgenic flax, devoid of (+) secoisolariciresinol diglucoside ((+) SDG)—the main flaxseed lignan, was performed using 1H-NMR and LC-MS, in order to obtain further insight into the involvement of lignan in the response of plant to osmotic stress. Results showed that wild-type and lignan-deficient flax plants have different metabolic responses after being exposed to osmotic stress conditions, but they both showed the capacity to induce an adaptive response to osmotic stress. These findings suggest the indirect involvement of lignans in osmotic stress response.

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A Novel CO-Responsive Transcriptional Regulator and Enhanced H2Production by an Engineered Thermococcus onnurineus NA1 Strain

Applied and Environmental Microbiology ◽

10.1128/aem.03019-14 ◽

2014 ◽

Vol 81 (5) ◽

pp. 1708-1714 ◽

Cited By ~ 25

Author(s):

Min-Sik Kim ◽

Ae Ran Choi ◽

Seong Hyuk Lee ◽

Hae-Chang Jung ◽

Seung Seob Bae ◽

...

Keyword(s):

Production Rate ◽

Gene Cluster ◽

Type Strain ◽

Wild Type Strain ◽

Regulatory System ◽

Transcriptional Regulator ◽

Bioreactor Culture ◽

Wild Type ◽

Content Type ◽

Transcriptional Regulatory

ABSTRACTGenome analysis revealed the existence of a putative transcriptional regulatory system governing CO metabolism inThermococcus onnurineusNA1, a carboxydotrophic hydrogenogenic archaeon. The regulatory system is composed of CorQ with a 4-vinyl reductase domain and CorR with a DNA-binding domain of the LysR-type transcriptional regulator family in close proximity to the CO dehydrogenase (CODH) gene cluster. Homologous genes of the CorQR pair were also found in the genomes ofThermococcusspecies and “CandidatusKorarchaeum cryptofilum” OPF8. In-frame deletion of eithercorQorcorRcaused a severe impairment in CO-dependent growth and H2production. WhencorQandcorRdeletion mutants were complemented by introducing thecorQRgenes under the control of a strong promoter, the mRNA and protein levels of the CODH gene were significantly increased in a ΔCorR strain complemented with integratedcorQR(ΔCorR/corQR↑) compared with those in the wild-type strain. In addition, the ΔCorR/corQR↑strain exhibited a much higher H2production rate (5.8-fold) than the wild-type strain in a bioreactor culture. The H2production rate (191.9 mmol liter−1h−1) and the specific H2production rate (249.6 mmol g−1h−1) of this strain were extremely high compared with those of CO-dependent H2-producing prokaryotes reported so far. These results suggest that thecorQRgenes encode a positive regulatory protein pair for the expression of a CODH gene cluster. The study also illustrates that manipulation of the transcriptional regulatory system can improve biological H2production.

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Complex transcriptional regulation of the Saccharomyces cerevisiae CYB2 gene encoding cytochrome b2: CYP1(HAP1) activator binds to the CYB2 upstream activation site UAS1-B2.

Molecular and Cellular Biology ◽

10.1128/mcb.11.7.3762 ◽

1991 ◽

Vol 11 (7) ◽

pp. 3762-3772 ◽

Cited By ~ 36

Author(s):

T Lodi ◽

B Guiard

Keyword(s):

Saccharomyces Cerevisiae ◽

Regulatory Region ◽

Transcriptional Regulator ◽

Direct Analysis ◽

Transcriptional Level ◽

Glucose Fermentation ◽

Gene Encoding ◽

Dnase I Footprinting ◽

Mrna Transcripts ◽

Binding Sequence

Expression of the Saccharomyces cerevisiae gene encoding cytochrome b2 (EC 1.2.2.3), CYB2, was investigated by direct analysis of mRNA transcripts and by measurement of the expression of lacZ fused to the CYB2 control regions. These studies indicated that regulation of the CYB2 gene is subject to several metabolic controls at the transcriptional level: inhibition due to glucose fermentation, induction by lactate, and inhibition in anaerobiosis or in absence of heme biosynthesis. Furthermore, we have shown that the CYB2 promoter contains one cis negative regulatory region and two heme-dependent positive regions, one of which is controlled by the transcriptional regulator CYP1 (HAP1) which is involved in the modulation of the expression of several oxygen-regulated genes. The CYP1 (HAP1)-binding sequence was located by gel retardation and DNase I footprinting experiments and compared with the binding sequences previously characterized in detail (UAS1CYC1, UAS'CYP3 (CYC7), and UASCTT1).

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