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 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.

The Role of Reactive Oxygen Species in Tumor Treatment and its Impact on Bone Marrow Hematopoiesis

2020 ◽  
Vol 21 (5) ◽  
pp. 477-498
Author(s):  
Yongfeng Chen ◽  
Xingjing Luo ◽  
Zhenyou Zou ◽  
Yong Liang
Keyword(s):  
Reactive Oxygen Species ◽  
Bone Marrow ◽  
Oxidative Damage ◽  
Tumor Cells ◽  
Reactive Oxygen ◽  
Oxygen Species ◽  
Tumor Treatment ◽  
Normal Cells ◽  
Treatment And Prevention

Reactive oxygen species (ROS), an important molecule inducing oxidative stress in organisms, play a key role in tumorigenesis, tumor progression and recurrence. Recent findings on ROS have shown that ROS can be used to treat cancer as they accelerate the death of tumor cells. At present, pro-oxidant drugs that are intended to increase ROS levels of the tumor cells have been widely used in the clinic. However, ROS are a double-edged sword in the treatment of tumors. High levels of ROS induce not only the death of tumor cells but also oxidative damage to normal cells, especially bone marrow hemopoietic cells, which leads to bone marrow suppression and (or) other side effects, weak efficacy of tumor treatment and even threatening patients’ life. How to enhance the killing effect of ROS on tumor cells while avoiding oxidative damage to the normal cells has become an urgent issue. This study is a review of the latest progress in the role of ROS-mediated programmed death in tumor treatment and prevention and treatment of oxidative damage in bone marrow induced by ROS.

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