scholarly journals Ornithine Decarboxylase-Mediated Production of Putrescine Influences Ganoderic Acid Biosynthesis by Regulating Reactive Oxygen Species in Ganoderma lucidum

2017 ◽  
Vol 83 (20) ◽  
Author(s):  
Chen-Gao Wu ◽  
Jia-Long Tian ◽  
Rui Liu ◽  
Peng-Fei Cao ◽  
Tian-Jun Zhang ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Ornithine Decarboxylase ◽  
Ganoderma Lucidum ◽  
Oxygen Species ◽  
Ganoderic Acid ◽  
Gene Encoding ◽  
Transcript Levels ◽  
Content Type ◽  
Future Studies

ABSTRACT Putrescine is an important polyamine that participates in a variety of stress responses. Ornithine decarboxylase (ODC) is a key enzyme that catalyzes the biosynthesis of putrescine. A homolog of the gene encoding ODC was cloned from Ganoderma lucidum. In the ODC-silenced strains, the transcript levels of the ODC gene and the putrescine content were significantly decreased. The ODC-silenced strains were more sensitive to oxidative stress. The content of ganoderic acid was increased by approximately 43 to 46% in the ODC-silenced strains. The content of ganoderic acid could be recovered after the addition of exogenous putrescine. Additionally, the content of reactive oxygen species (ROS) was significantly increased by approximately 1.3-fold in the ODC-silenced strains. The ROS content was significantly reduced after the addition of exogenous putrescine. The gene transcript levels and the activities of four major antioxidant enzymes were measured to further explore the effect of putrescine on the intracellular ROS levels. Further studies showed that the effect of the ODC-mediated production of putrescine on ROS might be a factor influencing the biosynthesis of ganoderic acid. Our study reports the role of putrescine in large basidiomycetes, providing a basis for future studies of the physiological functions of putrescine in microbes. IMPORTANCE It is well known that ODC and the ODC-mediated production of putrescine play an important role in resisting various environmental stresses, but there are few reports regarding the mechanisms underlying the effect of putrescine on secondary metabolism in microorganisms, particularly in fungi. G. lucidum is gradually becoming a model organism for studying environmental regulation and metabolism. In this study, a homolog of the gene encoding ODC was cloned in Ganoderma lucidum. We found that the transcript level of the ODC gene and the content of putrescine were significantly decreased in the ODC-silenced strains. The content of ganoderic acid was significantly increased in the ODC-silenced strains. Further studies showed that the effect of the ODC-mediated production of putrescine on ROS might be a factor influencing the biosynthesis of ganoderic acid. Our study reports the role of putrescine in large basidiomycetes, providing a basis for future studies of the physiological functions of putrescine in microbes.

Functions of reactive oxygen species in apoptosis and ganoderic acid biosynthesis in Ganoderma lucidum

2019 ◽  
Vol 366 (23) ◽  
Author(s):  
Jing Zhu ◽  
Fengli Wu ◽  
Sining Yue ◽  
Chen Chen ◽  
Shuqi Song ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Ganoderma Lucidum ◽  
Reactive Oxygen ◽  
Terminal Deoxynucleotidyl Transferase ◽  
Activity Levels ◽  
Oxygen Species ◽  
Ganoderic Acid ◽  
Medicinal Fungus ◽  
Intracellular Ros ◽  
Ga Biosynthesis

ABSTRACT Ganoderma lucidum is a medicinal fungus that is widely used in traditional medicine. Fungal PacC is recognized as an important transcription factor that functions during adaptation to environmental pH, fungal development and secondary metabolism. Previous studies have revealed that GlPacC plays important roles in mycelial growth, fruiting body development and ganoderic acid (GA) biosynthesis. In this study, using a terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) assay, we found that the apoptosis level was increased when PacC was silenced. The transcript and activity levels of caspase-like proteins were significantly increased in the PacC-silenced (PacCi) strains compared with the control strains. Silencing PacC also resulted in an increased reactive oxygen species (ROS) levels (∼2-fold) and decreased activity levels of enzymes involved in the antioxidant system. Further, we found that the intracellular ROS levels contributed to apoptosis and GA biosynthesis. Adding N-acetyl-cysteine and vitamin C decreased intracellular ROS and resulted in the inhibition of apoptosis in the PacCi strains. Additionally, the GA biosynthesis was different between the control strains and the PacCi strains after intracellular ROS was eliminated. Taken together, the findings showed that silencing PacC can result in an intracellular ROS burst, which increases cell apoptosis and GA biosynthesis levels. Our study provides novel insight into the functions of PacC in filamentous fungi.

scholarly journals A Small-Molecule Modulator of Metal Homeostasis in Gram-Positive Pathogens

mBio ◽  
2020 ◽  
Vol 11 (5) ◽  
Author(s):  
Lillian J. Juttukonda ◽  
William N. Beavers ◽  
Daisy Unsihuay ◽  
Kwangho Kim ◽  
Gleb Pishchany ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Small Molecule ◽  
Metal Uptake ◽  
Reactive Oxygen ◽  
Metal Homeostasis ◽  
Oxygen Species ◽  
Gram Positive ◽  
Content Type ◽  
Gram Positive Bacteria

ABSTRACT Metals are essential nutrients that all living organisms acquire from their environment. While metals are necessary for life, excess metal uptake can be toxic; therefore, intracellular metal levels are tightly regulated in bacterial cells. Staphylococcus aureus, a Gram-positive bacterium, relies on metal uptake and metabolism to colonize vertebrates. Thus, we hypothesized that an expanded understanding of metal homeostasis in S. aureus will lead to the discovery of pathways that can be targeted with future antimicrobials. We sought to identify small molecules that inhibit S. aureus growth in a metal-dependent manner as a strategy to uncover pathways that maintain metal homeostasis. Here, we demonstrate that VU0026921 kills S. aureus through disruption of metal homeostasis. VU0026921 activity was characterized through cell culture assays, transcriptional sequencing, compound structure-activity relationship, reactive oxygen species (ROS) generation assays, metal binding assays, and metal level analyses. VU0026921 disrupts metal homeostasis in S. aureus, increasing intracellular accumulation of metals and leading to toxicity through mismetalation of enzymes, generation of reactive oxygen species, or disruption of other cellular processes. Antioxidants partially protect S. aureus from VU0026921 killing, emphasizing the role of reactive oxygen species in the mechanism of killing, but VU0026921 also kills S. aureus anaerobically, indicating that the observed toxicity is not solely oxygen dependent. VU0026921 disrupts metal homeostasis in multiple Gram-positive bacteria, leading to increased reactive oxygen species and cell death, demonstrating the broad applicability of these findings. Further, this study validates VU0026921 as a probe to further decipher mechanisms required to maintain metal homeostasis in Gram-positive bacteria. IMPORTANCE Staphylococcus aureus is a leading agent of antibiotic-resistant bacterial infections in the world. S. aureus tightly controls metal homeostasis during infection, and disruption of metal uptake systems impairs staphylococcal virulence. We identified small molecules that interfere with metal handling in S. aureus to develop chemical probes to investigate metallobiology in this organism. Compound VU0026921 was identified as a small molecule that kills S. aureus both aerobically and anaerobically. The activity of VU0026921 is modulated by metal supplementation, is enhanced by genetic inactivation of Mn homeostasis genes, and correlates with increased cellular reactive oxygen species. Treatment with VU0026921 causes accumulation of multiple metals within S. aureus cells and concomitant upregulation of genes involved in metal detoxification. This work defines a small-molecule probe for further defining the role of metal toxicity in S. aureus and validates future antibiotic development targeting metal toxicity pathways.

scholarly journals Chemotaxis Allows Bacteria To Overcome Host-Generated Reactive Oxygen Species That Constrain Gland Colonization

2018 ◽  
Vol 86 (5) ◽  
pp. e00878-17 ◽  
Author(s):  
Kieran D. Collins ◽  
Shuai Hu ◽  
Helmut Grasberger ◽  
John Y. Kao ◽  
Karen M. Ottemann
Keyword(s):  
Reactive Oxygen Species ◽  
Immune Cell ◽  
Bacterial Chemotaxis ◽  
Reactive Oxygen ◽  
Innate Immune ◽  
Oxygen Species ◽  
Content Type ◽  
H Pylori ◽  
Number Of Bacteria

ABSTRACT The epithelial layer of the gastrointestinal tract contains invaginations, called glands or crypts, which are colonized by symbiotic and pathogenic microorganisms and may function as designated niches for certain species. Factors that control gland colonization are poorly understood, but bacterial chemotaxis aids occupation of these sites. We report here that a Helicobacter pylori cytoplasmic chemoreceptor, TlpD, is required for gland colonization in the stomach. tlpD mutants demonstrate gland colonization defects characterized by a reduction in the percentage of glands colonized but not in the number of bacteria per gland. Consistent with TlpD's reported role in reactive oxygen species (ROS) avoidance, tlpD mutants showed hallmarks of exposure to high ROS. To assess the role of host-generated ROS in TlpD-dependent gland colonization, we utilized mice that lack either the ability to generate epithelial hydrogen peroxide or immune cell superoxide. tlpD gland colonization defects were rescued to wild-type H. pylori levels in both of these mutants. These results suggest that multiple types of innate immune-generated ROS production limit gland colonization and that bacteria have evolved specific mechanisms to sense and direct their motility in response to this signal and thus spread throughout tissue.

scholarly journals SrrAB Modulates Staphylococcus aureus Cell Death through Regulation ofcidABCTranscription

2016 ◽  
Vol 198 (7) ◽  
pp. 1114-1122 ◽  
Author(s):  
Ian H. Windham ◽  
Sujata S. Chaudhari ◽  
Jeffrey L. Bose ◽  
Vinai C. Thomas ◽  
Kenneth W. Bayles
Keyword(s):  
Reactive Oxygen Species ◽  
Staphylococcus Aureus ◽  
Cell Death ◽  
Reactive Oxygen ◽  
Extracellular Dna ◽  
Death Process ◽  
Oxygen Species ◽  
Content Type ◽  
Biofilm Development

ABSTRACTThe death and lysis of a subpopulation inStaphylococcus aureusbiofilm cells are thought to benefit the surviving population by releasing extracellular DNA, a critical component of the biofilm extracellular matrix. Although the means by whichS. aureuscontrols cell death and lysis is not understood, studies implicate the role of thecidABCandlrgABoperons in this process. Recently, disruption of thesrrABregulatory locus was found to cause increased cell death during biofilm development, likely as a result of the sensitivity of this mutant to hypoxic growth. In the current study, we extended these findings by demonstrating that cell death in the ΔsrrABmutant is dependent on expression of thecidABCoperon. The effect ofcidABCexpression resulted in the generation of increased reactive oxygen species (ROS) accumulation and was independent of acetate production. Interestingly, consistently with previous studies,cidC-encoded pyruvate oxidase was found to be important for the generation of acetic acid, which initiates the cell death process. However, these studies also revealed for the first time an important role of thecidBgene in cell death, as disruption ofcidBin the ΔsrrABmutant background decreased ROS generation and cell death in acidC-independent manner. ThecidBmutation also caused decreased sensitivity to hydrogen peroxide, which suggests a complex role for this system in ROS metabolism. Overall, the results of this study provide further insight into the function of thecidABCoperon in cell death and reveal its contribution to the oxidative stress response.IMPORTANCEThe manuscript focuses on cell death mechanisms inStaphylococcus aureusand provides important new insights into the genes involved in this ill-defined process. By exploring the cause of increased stationary-phase death in anS. aureusΔsrrABregulatory mutant, we found that the decreased viability of this mutant was a consequence of the overexpression of thecidABCoperon, previously shown to be a key mediator of cell death. These investigations highlight the role of thecidBgene in the death process and the accumulation of reactive oxygen species. Overall, the results of this study are the first to demonstrate a positive role for CidB in cell death and to provide an important paradigm for understanding this process in all bacteria.

scholarly journals Cross Talk between Nitric Oxide and Calcium-Calmodulin Regulates Ganoderic Acid Biosynthesis in Ganoderma lucidum under Heat Stress

2018 ◽  
Vol 84 (10) ◽  
pp. e00043-18 ◽  
Author(s):  
Rui Liu ◽  
Liang Shi ◽  
Ting Zhu ◽  
Tao Yang ◽  
Ang Ren ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Heat Stress ◽  
Ganoderma Lucidum ◽  
Ganoderic Acid ◽  
No Donor ◽  
Content Type ◽  
Fungal Biology ◽  
Close Relationship ◽  
Ga Biosynthesis

ABSTRACT We previously reported that high temperature impacts ganoderic acid (GA) biosynthesis in Ganoderma lucidum via Ca2+. Therefore, to further understand the signal-regulating network of the organism's response to heat stress (HS), we examined the role of nitric oxide (NO) under HS. After HS treatment, the NO level was significantly increased by 120% compared to that under the control conditions. The application of a NO scavenger resulted in a 25% increase in GA compared with that found in the sample treated only with HS. Additionally, the application of a NO donor to increase NO resulted in a 30% lower GA content than that in the sample treated only with HS. These results show that the increase in NO levels alleviates HS-induced GA accumulation. Subsequently, we aimed to detect the effects of the interaction between NO and Ca2+ on GA biosynthesis under HS in G. lucidum. Our pharmacological approaches revealed that the NO and Ca2+ signals promoted each other in response to HS. We further constructed the silenced strain of nitrate reductase (NR) and calmodulin (CaM), and the results are in good agreement with the silenced strain and pharmacological experiment. The cross-promotion between NO and Ca2+ signals is involved in the regulation of HS-induced GA biosynthesis in G. lucidum, and this finding is supported by studies with NR-silenced (NRi) and CaM-silenced (CaMi) strains. However, Ca2+ may have a more direct and significant effect on the HS-induced GA increase than NO. These data indicate that NO functions in signaling and has a close relationship with Ca2+ in HS-induced GA biosynthesis. IMPORTANCE HS is an important environmental stress affecting the growth and development of organisms. We previously reported that HS modulates GA biosynthesis in G. lucidum via Ca2+. However, the signal-regulating network of the organism's response to HS has not yet been elucidated. In this study, we found that NO relieved HS-induced GA accumulation, and NO and Ca2+ could exert promoting effects on each other in response to HS. Further research on the effect of NO and Ca2+ on the production of GAs in response to HS indicated that Ca2+ has a notably more direct and significant effect on the HS-induced GA increase than NO. Our results improve our understanding of the mechanism of HS signal transduction in fungi. A greater understanding of the regulation of secondary metabolism in response to environmental stimuli will provide clues regarding the role of these products in fungal biology.

scholarly journals CD157 Confers Host Resistance to Mycobacterium tuberculosis via TLR2-CD157-PKCzeta-Induced Reactive Oxygen Species Production

mBio ◽  
2019 ◽  
Vol 10 (4) ◽  
Author(s):  
Qianting Yang ◽  
Mingfeng Liao ◽  
Wenfei Wang ◽  
Mingxia Zhang ◽  
Qi Chen ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Mycobacterium Tuberculosis ◽  
Host Resistance ◽  
Ros Production ◽  
Oxygen Species ◽  
Effective Strategy ◽  
Content Type ◽  
Protein Levels

ABSTRACT Recruitment of monocytes to the infection site is critical for host resistance against Mycobacterium tuberculosis. CD157 has a crucial role in neutrophil and monocyte transendothelial migration and adhesion, but its role in tuberculosis (TB) is unclear. Here, we show that both mRNA and protein levels of Cd157 are significantly increased during M. tuberculosis infection. Deficiency of Cd157 impaired host response to M. tuberculosis infection by increasing bacterial burden and inflammation in the lung in the murine TB model. In vitro experiments show that the bactericidal ability was compromised in Cd157 knockout (KO) macrophages, which was due to impaired M. tuberculosis-induced reactive oxygen species (ROS) production. We further reveal that CD157 interacts with TLR2 and PKCzeta and facilitates M. tuberculosis-induced ROS production in Cd157 KO macrophages, which resulted in enhanced M. tuberculosis killing. For the clinic aspect, we observe that the expression of CD157 decreases after effective anti-TB chemotherapy. CD157 is specifically increased in pleural fluid in tuberculous pleurisy patients compared to pneumonia and lung cancer patients. Interestingly, the levels of soluble CD157 (sCD157) correlate with human peripheral monocyte-derived macrophage bactericidal activity. Exogenous application of sCD157 could compensate for macrophage bactericidal ability and restore ROS production. In conclusion, we have identified a novel protective immune function of CD157 during M. tuberculosis infection via TLR2-dependent ROS production. Application of sCD157 might be an effective strategy for host-directed therapy against TB in those with insufficient CD157 production. IMPORTANCE Tuberculosis, a chronic bacterial disease caused by Mycobacterium tuberculosis, remains a major global health problem. CD157, a dual-function receptor and β-NAD+-metabolizing ectoenzyme, promotes cell polarization, regulates chemotaxis induced through the high-affinity fMLP receptor, and controls transendothelial migration. The role of CD157 in TB pathogenesis remains unknown. In this study, we find that both mRNA and protein levels of CD157 are significantly increased in TB. Deficiency of CD157 impaired host defense against M. tuberculosis infection both in vivo and in vitro, which is mediated by an interaction among CD157, TLR2, and PKCzeta. This interaction facilitates M. tuberculosis-induced macrophagic ROS production, which enhances macrophage bactericidal activity. Interestingly, the sCD157 level in plasma is reversibly associated with MDM M. tuberculosis killing activity. By uncovering the role of CD157 in pathogenesis of TB for the first time, our work demonstrated that application of soluble CD157 might be an effective strategy for host-directed therapy against TB.

scholarly journals Cross Talk between Calcium and Reactive Oxygen Species Regulates Hyphal Branching and Ganoderic Acid Biosynthesis in Ganoderma lucidum under Copper Stress

2018 ◽  
Vol 84 (13) ◽  
pp. e00438-18 ◽  
Author(s):  
Tan Gao ◽  
Liang Shi ◽  
Tianjun Zhang ◽  
Ang Ren ◽  
Ailiang Jiang ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Cross Talk ◽  
Ganoderma Lucidum ◽  
Reactive Oxygen ◽  
Hyphal Growth ◽  
Oxygen Species ◽  
Ganoderic Acid ◽  
Hyphal Branching ◽  
Ga Content ◽  
Ga Biosynthesis

ABSTRACT Ganoderma lucidum is among the best known medicinal basidiomycetes due to its production of many pharmacologically active compounds. To study the regulatory networks involved in its growth and development, we analyzed the relationship between reactive oxygen species (ROS) and Ca2+ signaling in the regulation of hyphal branching and ganoderic acid (GA) biosynthesis after Cu2+ treatment. Our results revealed that Cu2+ treatment decreased the distance between hyphal branches and increased the GA content and the intracellular levels of ROS and Ca2+. Further research revealed that the Cu2+-induced changes in hyphal branch distance, GA content, and cytosolic Ca2+ level were dependent on increases in cytosolic ROS. Our results also showed that increased cytosolic Ca2+ could reduce cytosolic ROS by activating antioxidases and modulating Cu2+ accumulation, resulting in feedback to adjust hyphal growth and GA biosynthesis. These results indicated that cytosolic ROS and Ca2+ levels exert important cross talk in the regulation of hyphal growth and GA biosynthesis induced by Cu2+. Taken together, our results provide a reference for analyzing the interactions among different signal transduction pathways with regard to the regulation of growth and development in other filamentous fungi. IMPORTANCE Ganoderma lucidum, which is known as an important medicinal basidiomycete, is gradually becoming a model organism for studying environmental regulation and metabolism. In this study, we analyzed the relationship between reactive oxygen species (ROS) and Ca2+ signaling in the regulation of hyphal branching and ganoderic acid (GA) biosynthesis under Cu2+ stress. The results revealed that the Cu2+-induced changes in the hyphal branch distance, GA content, and cytosolic Ca2+ level were dependent on increases in cytosolic ROS. Furthermore, the results indicated that increased cytosolic Ca2+ could reduce cytosolic ROS levels by activating antioxidases and modulating Cu2+ accumulation. The results in this paper indicate that there was important cross talk between cytosolic ROS and Ca2+ levels in the regulation of hyphal growth and GA biosynthesis induced by Cu2+.

scholarly journals Role of Bacillus subtilis DNA Glycosylase MutM in Counteracting Oxidatively Induced DNA Damage and in Stationary-Phase-Associated Mutagenesis

2015 ◽  
Vol 197 (11) ◽  
pp. 1963-1971 ◽  
Author(s):  
Martha Gómez-Marroquín ◽  
Luz E. Vidales ◽  
Bernardo N. Debora ◽  
Fernando Santos-Escobar ◽  
Armando Obregón-Herrera ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Hydrogen Peroxide ◽  
Dna Damage ◽  
Bacillus Subtilis ◽  
Stationary Phase ◽  
Reactive Oxygen ◽  
Dna Glycosylase ◽  
Oxygen Species ◽  
Content Type

ABSTRACTReactive oxygen species (ROS) promote the synthesis of the DNA lesion 8-oxo-G, whose mutagenic effects are counteracted in distinct organisms by the DNA glycosylase MutM. We report here that inBacillus subtilis,mutMis expressed during the exponential and stationary phases of growth. In agreement with this expression pattern, results of a Western blot analysis confirmed the presence of MutM in both stages of growth. In comparison with cells of a wild-type strain, cells ofB. subtilislacking MutM increased their spontaneous mutation frequency to Rifrand were more sensitive to the ROS promoter agents hydrogen peroxide and 1,1′-dimethyl-4,4′-bipyridinium dichloride (Paraquat). However, despite MutM's proven participation in preventing ROS-induced-DNA damage, the expression ofmutMwas not induced by hydrogen peroxide, mitomycin C, or NaCl, suggesting that transcription of this gene is not under the control of the RecA, PerR, or σBregulons. Finally, the role of MutM in stationary-phase-associated mutagenesis (SPM) was investigated in the strainB. subtilisYB955 (hisC952 metB5 leuC427). Results revealed that under limiting growth conditions, amutMknockout strain significantly increased the amount of stationary-phase-associatedhis,met, andleurevertants produced. In summary, our results support the notion that the absence of MutM promotes mutagenesis that allows nutritionally stressedB. subtiliscells to escape from growth-limiting conditions.IMPORTANCEThe present study describes the role played by a DNA repair protein (MutM) in protecting the soil bacteriumBacillus subtilisfrom the genotoxic effects induced by reactive oxygen species (ROS) promoter agents. Moreover, it reveals that the genetic inactivation ofmutMallows nutritionally stressed bacteria to escape from growth-limiting conditions, putatively by a mechanism that involves the accumulation and error-prone processing of oxidized DNA bases.

Sign in / Sign up

Export Citation Format

Share Document