scholarly journals Identification of a Regulator That Controls Stationary-Phase Expression of Catalase-Peroxidase in Caulobacter crescentus

1999 ◽  
Vol 181 (19) ◽  
pp. 6152-6159 ◽  
Author(s):  
Paul S. Rava ◽  
Laura Somma ◽  
Howard M. Steinman
Keyword(s):  
Hydrogen Peroxide ◽  
Stress Response ◽  
Stationary Phase ◽  
Caulobacter Crescentus ◽  
Sequence Similarity ◽  
Enteric Bacteria ◽  
Cross Resistance ◽  
Peptide Antibiotic ◽  
Reading Frame ◽  
Catalase Peroxidase

ABSTRACT Expression of the catalase-peroxidase of Caulobacter crescentus, a gram-negative member of the α subdivision of theProteobacteria, is 50-fold higher in stationary-phase cultures than in exponential cultures. To identify regulators of the starvation response, Tn5 insertion mutants were isolated with reduced expression of a katG::lacZ fusion on glucose starvation. One insertion interrupted an open reading frame encoding a protein with significant amino acid sequence identity to TipA, a helix-turn-helix transcriptional activator in the response ofStreptomyces lividans to the peptide antibiotic thiostrepton, and lesser sequence similarity to other helix-turn-helix regulators in the MerR family. The C. crescentus orthologue of tipA was named skgA (stationary-phase regulation of katG). Stationary-phase expression ofkatG was reduced by 70% in theskgA::Tn5 mutant, and stationary-phase resistance to hydrogen peroxide decreased by a factor of 10. Like the wild type, the skgA mutant exhibited starvation-induced cross-resistance to heat and acid shock, entered into the helical morphology that occurs after 9 to 12 days in stationary phase, and during exponential growth inducedkatG in response to hydrogen peroxide challenge. Expression of skgA increased 5- to 10-fold in late exponential phase.skgA is the first regulator of a starvation-induced stress response identified in C. crescentus. SkgA is not a global regulator of the stationary-phase stress response; its action encompasses the oxidative stress-hydrogen peroxide response but not acid or heat responses. Moreover, SkgA is not an alternative ς factor, like RpoS, which controls multiple aspects of starvation-induced cross-resistance to stress in enteric bacteria. These observations raise the possibility that regulation of stationary-phase gene expression in this member of the α subdivision of the Proteobacteria is different from that inEscherichia coli and other members of the γ subdivision.

scholarly journals Halocin S8: a 36-Amino-Acid Microhalocin from the Haloarchaeal Strain S8a

2000 ◽  
Vol 182 (17) ◽  
pp. 4951-4958 ◽  
Author(s):  
Lance B. Price ◽  
Richard F. Shand
Keyword(s):  
Amino Acid ◽  
Stationary Phase ◽  
Growth Stage ◽  
Northern Blot Analysis ◽  
Open Reading Frame ◽  
Peptide Antibiotic ◽  
Edman Degradation ◽  
Transcript Levels ◽  
Reading Frame ◽  
Low Concentrations

ABSTRACT Halocin S8 is a hydrophobic microhalocin of 36 amino acids (3,580 Da) and is the first microhalocin to be described. This peptide antibiotic is unique since it is processed from inside a much larger, 33,962-Da pro-protein. Halocin S8 is quite robust, as it can be desalted, boiled, subjected to organic solvents, and stored at 4°C for extended periods without losing activity. The complete amino acid sequence of halocin S8 was obtained first by Edman degradation of the purified protein and verified from the halS8 gene: H2N-S-D-C-N-I-N-S-N-T-A-A-D-V-I-L-C-F-N-Q-V-G-S-C-A-L-C-S-P-T-L-V-G-G-P-V-P-COOH. The halS8 gene is encoded on an ∼200-kbp megaplasmid and contains a 933-bp open reading frame, of which 108 bp are occupied by halocin S8. Both the halS8 promoter and the “leaderless” halS8 transcript are typically haloarchaeal. Northern blot analysis revealed three halS8transcripts: two abundant and one minor. Inspection of the 3′ end of the gene showed only a single, weak termination site (5′-TTTAT-3′), suggesting that some processing of the larger transcripts may be involved. Expression of the halS8 gene is growth stage dependent: basal halS8 transcript levels are present in low concentrations during exponential growth but increase ninefold during the transition to stationary phase. Initially, halocin activity parallels halS8 transcript levels very closely. However, when halocin activity plateaus, transcripts remain abundant, suggesting inhibition of translation at this point. Once the culture enters stationary phase, transcripts rapidly return to basal levels.

scholarly journals OxyR and the hydrogen peroxide stress response in Caulobacter crescentus

Gene ◽  
2019 ◽  
Vol 700 ◽  
pp. 70-84 ◽  
Author(s):  
Larissa G. Silva ◽  
Alan P.R. Lorenzetti ◽  
Rodolfo A. Ribeiro ◽  
Ingrid R. Alves ◽  
Laura Leaden ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Stress Response ◽  
Caulobacter Crescentus ◽  
Peroxide Stress

scholarly journals The Potential of Human Peptide LL-37 as an Antimicrobial and Anti-Biofilm Agent

Antibiotics ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 650
Author(s):  
Kylen E. Ridyard ◽  
Joerg Overhage
Keyword(s):  
Bacterial Infections ◽  
Antimicrobial Properties ◽  
Cross Resistance ◽  
Resistant Bacteria ◽  
Peptide Antibiotic ◽  
Adaptive Responses ◽  
Antibiotic Resistant ◽  
Structural Modifications ◽  
Immobilization Techniques ◽  
Conventional Antibiotics

The rise in antimicrobial resistant bacteria threatens the current methods utilized to treat bacterial infections. The development of novel therapeutic agents is crucial in avoiding a post-antibiotic era and the associated deaths from antibiotic resistant pathogens. The human antimicrobial peptide LL-37 has been considered as a potential alternative to conventional antibiotics as it displays broad spectrum antibacterial and anti-biofilm activities as well as immunomodulatory functions. While LL-37 has shown promising results, it has yet to receive regulatory approval as a peptide antibiotic. Despite the strong antimicrobial properties, LL-37 has several limitations including high cost, lower activity in physiological environments, susceptibility to proteolytic degradation, and high toxicity to human cells. This review will discuss the challenges associated with making LL-37 into a viable antibiotic treatment option, with a focus on antimicrobial resistance and cross-resistance as well as adaptive responses to sub-inhibitory concentrations of the peptide. The possible methods to overcome these challenges, including immobilization techniques, LL-37 delivery systems, the development of LL-37 derivatives, and synergistic combinations will also be considered. Herein, we describe how combination therapy and structural modifications to the sequence, helicity, hydrophobicity, charge, and configuration of LL-37 could optimize the antimicrobial and anti-biofilm activities of LL-37 for future clinical use.

scholarly journals Environmental Conditions Modulate the Transcriptomic Response of Both Caulobacter crescentus Morphotypes to Cu Stress

2021 ◽  
Vol 9 (6) ◽  
pp. 1116
Author(s):  
Laurens Maertens ◽  
Pauline Cherry ◽  
Françoise Tilquin ◽  
Rob Van Houdt ◽  
Jean-Yves Matroule
Keyword(s):  
Oxidative Stress ◽  
Stress Response ◽  
Stress Responses ◽  
Caulobacter Crescentus ◽  
Oxidative Stress Response ◽  
Transport Systems ◽  
Transcriptomic Response ◽  
Swarmer Cell ◽  
Cu Stress ◽  
Cellular Environment

Bacteria encounter elevated copper (Cu) concentrations in multiple environments, varying from mining wastes to antimicrobial applications of copper. As the role of the environment in the bacterial response to Cu ion exposure remains elusive, we used a tagRNA-seq approach to elucidate the disparate responses of two morphotypes of Caulobacter crescentus NA1000 to moderate Cu stress in a complex rich (PYE) medium and a defined poor (M2G) medium. The transcriptome was more responsive in M2G, where we observed an extensive oxidative stress response and reconfiguration of the proteome, as well as the induction of metal resistance clusters. In PYE, little evidence was found for an oxidative stress response, but several transport systems were differentially expressed, and an increased need for histidine was apparent. These results show that the Cu stress response is strongly dependent on the cellular environment. In addition, induction of the extracytoplasmic function sigma factor SigF and its regulon was shared by the Cu stress responses in both media, and its central role was confirmed by the phenotypic screening of a sigF::Tn5 mutant. In both media, stalked cells were more responsive to Cu stress than swarmer cells, and a stronger basal expression of several cell protection systems was noted, indicating that the swarmer cell is inherently more Cu resistant. Our approach also allowed for detecting several new transcription start sites, putatively indicating small regulatory RNAs, and additional levels of Cu-responsive regulation.

scholarly journals Overexpression of the pitaya phosphoethanolamine N-methyltransferase gene (HpPEAMT) enhanced simulated drought stress in tobacco

2021 ◽  
Author(s):  
Ai-Hua Wang ◽  
Lan Yang ◽  
Xin-Zhuan Yao ◽  
Xiao-Peng Wen
Keyword(s):  
Drought Stress ◽  
Stress Response ◽  
Transgenic Plants ◽  
Drought Tolerance ◽  
Transgenic Tobacco ◽  
Sequence Similarity ◽  
Amino Acid Sequence Similarity ◽  
Transgenic Tobacco Plants ◽  
Wild Type ◽  
Tobacco Plants

AbstractPhosphoethanolamine N-methyltransferase (PEAMTase) catalyzes the methylation of phosphoethanolamine to produce phosphocholine and plays an important role in the abiotic stress response. Although the PEAMT genes has been isolated from many species other than pitaya, its role in the drought stress response has not yet been fully elucidated. In the present study, we isolated a 1485 bp cDNA fragment of HpPEAMT from pitaya (Hylocereus polyrhizus). Phylogenetic analysis showed that, during its evolution, HpPEAMT has shown a high degree of amino acid sequence similarity with the orthologous genes in Chenopodiaceae species. To further investigate the function of HpPEAMT, we generated transgenic tobacco plants overexpressing HpPEAMT, and the transgenic plants accumulated significantly more glycine betaine (GB) than did the wild type (WT). Drought tolerance trials indicated that, compared with those of the wild-type (WT) plants, the roots of the transgenic plants showed higher drought tolerance ability and exhibited improved drought tolerance. Further analysis revealed that overexpression of HpPEAM in Nicotiana tabacum resulted in upregulation of transcript levels of GB biosynthesis-related genes (NiBADH, NiCMO and NiSDC) in the leaves. Furthermore, compared with the wild-type plants, the transgenic tobacco plants displayed a significantly lower malondialdehyde (MDA) accumulation and higher activities of the superoxide dismutase (SOD) and peroxidase (POD) antioxidant enzymes under drought stress. Taken together, our results suggested that HpPEAMT enhanced the drought tolerance of transgenic tobacco.

scholarly journals RpoS-Dependent Stress Response and Exoenzyme Production in Vibrio vulnificus

2003 ◽  
Vol 69 (10) ◽  
pp. 6114-6120 ◽  
Author(s):  
A. Hülsmann ◽  
T. M. Rosche ◽  
I.-S. Kong ◽  
H. M. Hassan ◽  
D. M. Beam ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Stress Response ◽  
Mutant Strain ◽  
Environmental Changes ◽  
Vibrio Vulnificus ◽  
High Sensitivity ◽  
Striking Difference ◽  
Wild Type ◽  
Hydrolytic Activities ◽  
In The Wild

ABSTRACT Vibrio vulnificus is an estuarine bacterium capable of causing rapidly fatal infections through both ingestion and wound infection. Like other opportunistic pathogens, V. vulnificus must adapt to potentially stressful environmental changes while living freely in seawater, upon colonization of the oyster gut, and upon infection of such diverse hosts as humans and eels. In order to begin to understand the ability of V. vulnificus to respond to such stresses, we examined the role of the alternate sigma factor RpoS, which is important in stress response and virulence in many pathogens. An rpoS mutant of V. vulnificus strain C7184o was constructed by homologous recombination. The mutant strain exhibited a decreased ability to survive diverse environmental stresses, including exposure to hydrogen peroxide, hyperosmolarity, and acidic conditions. The most striking difference was a high sensitivity of the mutant to hydrogen peroxide. Albuminase, caseinase, and elastase activity were detected in the wild type but not in the mutant strain, and an additional two hydrolytic activities (collagenase and gelatinase) were reduced in the mutant strain compared to the wild type. Additionally, the motility of the rpoS mutant was severely diminished. Overall, these studies suggest that rpoS in V. vulnificus is important for adaptation to environmental changes and may have a role in virulence.

scholarly journals Hormetic Concentrations of Hydrogen Peroxide but Not Ethanol Induce Cross-Adaptation to Different Stresses in Budding Yeast

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Halyna M. Semchyshyn
Keyword(s):  
Hydrogen Peroxide ◽  
Dose Response ◽  
Budding Yeast ◽  
Regulatory Protein ◽  
Colony Growth ◽  
Inhibitory Effect ◽  
Cross Resistance ◽  
Mild Stress ◽  
Low Concentrations ◽  
Cross Adaptation

The biphasic-dose response of microorganisms to hydrogen peroxide is a phenomenon of particular interest in hormesis research. In different animal models, the dose-response curve for ethanol is also nonlinear showing an inhibitory effect at high doses but a stimulatory effect at low doses. In this study, we observed the hormetic-dose response to ethanol in budding yeastS. cerevisiae. Cross-protection is a phenomenon in which exposure to mild stress results in the acquisition of cellular resistance to lethal stress induced by different factors. Since both hydrogen peroxide and ethanol at low concentrations were found to stimulate yeast colony growth, we evaluated the role of one substance in cell cross-adaptation to the other substance as well as some weak organic acid preservatives. This study demonstrates that, unlike ethanol, hydrogen peroxide at hormetic concentrations causes cross-resistance ofS. cerevisiaeto different stresses. The regulatory protein Yap1 plays an important role in the hormetic effects by low concentrations of either hydrogen peroxide or ethanol, and it is involved in the yeast cross-adaptation by low sublethal doses of hydrogen peroxide.

Sign in / Sign up

Export Citation Format

Share Document