-
Environmental Microbiology Sep 2021Xanthomonas oryzae pv. oryzae (Xoo) causes a serious disease of rice known as bacterial leaf blight. Several virulence-associated functions have been characterized in...
Xanthomonas oryzae pv. oryzae (Xoo) causes a serious disease of rice known as bacterial leaf blight. Several virulence-associated functions have been characterized in Xoo. However, the role of important second messenger c-di-GMP signalling in the regulation of virulence-associated functions still remains elusive in this phytopathogen. In this study we have performed an investigation of 13 c-di-GMP modulating deletion mutants to understand their contribution in Xoo virulence and lifestyle transition. We show that four Xoo proteins, Xoo2331, Xoo2563, Xoo2860 and Xoo2616, are involved in fine-tuning the in vivo c-di-GMP abundance and also play a role in the regulation of virulence-associated functions. We have further established the importance of the GGDEF domain of Xoo2563, a previously characterized c-di-GMP phosphodiesterase, in the virulence-associated functions of Xoo. Interestingly the strain harbouring the GGDEF domain deletion (ΔXoo2563 ) exhibited EPS deficiency and hypersensitivity to streptonigrin, indicative of altered iron metabolism. This is in contrast to the phenotype exhibited by an EAL overexpression strain wherein, the ΔXoo2563 exhibited other phenotypes, similar to the strain overexpressing the EAL domain. Taken together, our results indicate a complex interplay of c-di-GMP signalling with the cell-cell signalling to coordinate virulence-associated function in Xoo.
Topics: Bacterial Proteins; Cyclic GMP; Gene Expression Regulation, Bacterial; Plant Diseases; Virulence; Xanthomonas
PubMed: 34240791
DOI: 10.1111/1462-2920.15664 -
Plants (Basel, Switzerland) Jun 2024Lemon essential oil, derived from , possesses diverse health-promoting properties, including antioxidant, antimicrobial, and mood-enhancing effects. Despite its...
Lemon essential oil, derived from , possesses diverse health-promoting properties, including antioxidant, antimicrobial, and mood-enhancing effects. Despite its traditional use in aromatherapy and complementary medicine, there is a need for comprehensive investigations into its therapeutic potential, particularly in mitigating DNA damage and supporting health in palliative care settings. This study aimed to evaluate the antigenotoxic effects of lemon essential oil in human peripheral blood mononuclear cells and to explore its potential applications in palliative care. Treatment with lemon essential oil significantly reduced DNA damage, with 1% w/v with 3.13% DNA in tail demonstrating greater efficacy. Furthermore, lemon essential oil attenuated streptonigrin-induced DNA damage, suggesting a potential protective effect against oxidative stress, especially at 3% w/v, with 11.81% DNA in tail. Compared to olive oil treatment, the DNA damage was significantly lower with streptonigrin treatment alone, which had 47.06% DNA in tail, while the olive oil treatment resulted in 36.88% DNA in tail. These results can be attributed to the main constituents: limonene in lemon essential oil and oleic acid in olive oil. These results suggest a potential role in mitigating oxidative stress and supporting genomic stability. Further research is warranted to elucidate the mechanisms of action and clinical applications in palliative care.
PubMed: 38931055
DOI: 10.3390/plants13121623 -
Veterinary Research Mar 2021Iron is essential for most bacteria to survive, but excessive iron leads to damage by the Fenton reaction. Therefore, the concentration of intracellular free iron must...
Iron is essential for most bacteria to survive, but excessive iron leads to damage by the Fenton reaction. Therefore, the concentration of intracellular free iron must be strictly controlled in bacteria. Riemerella anatipestifer (R. anatipestifer), a Gram-negative bacterium, encodes the iron uptake system. However, the iron homeostasis mechanism remains largely unknown. In this study, it was shown that compared with the wild type R. anatipestifer CH-1, R. anatipestifer CH-1Δfur was more sensitive to streptonigrin, and this effect was alleviated when the bacteria were cultured in iron-depleted medium, suggesting that the fur mutant led to excess iron accumulation inside cells. Similarly, compared with R. anatipestifer CH-1∆recA, R. anatipestifer CH-1∆recAΔfur was more sensitive to HO-induced oxidative stress when the bacteria were grown in iron-rich medium rather than iron-depleted medium. Accordingly, it was shown that R. anatipestifer CH-1∆recAΔfur produced more intracellular ROS than R. anatipestifer CH-1∆recA in iron-rich medium. Electrophoretic mobility shift assays showed that R. anatipestifer CH-1 Fur suppressed the transcription of putative iron uptake genes through binding to their promoter regions. Finally, it was shown that compared with the wild type, R. anatipestifer CH-1Δfur was significantly attenuated in ducklings and that the colonization ability of R. anatipestifer CH-1Δfur in various tissues or organs was decreased. All these results suggested that Fur is important for iron homeostasis in R. anatipestifer and its pathogenic mechanism.
Topics: Bacterial Proteins; Iron; Oxidative Stress; Riemerella; Virulence
PubMed: 33741064
DOI: 10.1186/s13567-021-00919-9 -
Angewandte Chemie (International Ed. in... Jan 2023We report that axially chiral biaryl boronic esters can be generated with control of atroposelectivity by a Binol-mediated dynamic thermodynamic resolution process....
We report that axially chiral biaryl boronic esters can be generated with control of atroposelectivity by a Binol-mediated dynamic thermodynamic resolution process. These intermediates can be progressed to enantioenriched products through stereoretentive functionalization of the carbon-boron bond. Finally, we have exploited this method in the first highly stereoselective total synthesis of P-streptonigrin.
PubMed: 36377668
DOI: 10.1002/anie.202213692 -
The Journal of Antimicrobial... Jun 2024Riemerella anatipestifer encodes an iron acquisition system, but whether it encodes the iron efflux pump and its role in antibiotic resistance are largely unknown.
BACKGROUND
Riemerella anatipestifer encodes an iron acquisition system, but whether it encodes the iron efflux pump and its role in antibiotic resistance are largely unknown.
OBJECTIVES
To screen and identify an iron efflux gene in R. anatipestifer and determine whether and how the iron efflux gene is involved in antibiotic resistance.
METHODS
In this study, gene knockout, streptonigrin susceptibility assay and inductively coupled plasma mass spectrometry were used to screen for the iron efflux gene ietA. The MIC measurements, scanning electron microscopy and reactive oxygen species (ROS) detection were used to verify the role of IetA in aztreonam resistance and its mechanism. Mortality and colonization assay were used to investigate the role of IetA in virulence.
RESULTS
The deletion mutant ΔietA showed heightened susceptibility to streptonigrin, and prominent intracellular iron accumulation was observed in ΔfurΔietA under excess iron conditions. Additionally, ΔietA exhibited increased sensitivity to H2O2-produced oxidative stress. Under aerobic conditions with abundant iron, ΔietA displayed increased susceptibility to the β-lactam antibiotic aztreonam due to heightened ROS production. However, the killing efficacy of aztreonam was diminished in both WT and ΔietA under anaerobic or iron restriction conditions. Further experiments demonstrated that the efficiency of aztreonam against ΔietA was dependent on respiratory complexes Ⅰ and Ⅱ. Finally, in a duckling model, ΔietA had reduced virulence compared with the WT.
CONCLUSION
Iron efflux is critical to alleviate oxidative stress damage and β-lactam aztreonam killing in R. anatipestifer, which is linked by cellular respiration.
Topics: Oxidative Stress; Iron; Animals; Microbial Sensitivity Tests; Anti-Bacterial Agents; Riemerella; Aztreonam; Flavobacteriaceae Infections; Virulence; beta-Lactam Resistance; Ducks; Reactive Oxygen Species; Membrane Transport Proteins; Streptonigrin; Gene Knockout Techniques; Poultry Diseases; Bacterial Proteins
PubMed: 38629469
DOI: 10.1093/jac/dkae114 -
PloS One 2021The foodborne pathogen Listeria monocytogenes is able to survive across a wide range of intra- and extra-host environments by appropriately modulating gene expression...
The foodborne pathogen Listeria monocytogenes is able to survive across a wide range of intra- and extra-host environments by appropriately modulating gene expression patterns in response to different stimuli. Positive Regulatory Factor A (PrfA) is the major transcriptional regulator of virulence gene expression in L. monocytogenes. It has long been known that activated charcoal is required to induce the expression of PrfA-regulated genes in complex media, such as Brain Heart Infusion (BHI), but not in chemically defined media. In this study, we show that the expression of the PrfA-regulated hly, which encodes listeriolysin O, is induced 5- and 8-fold in L. monocytogenes cells grown in Chelex-treated BHI (Ch-BHI) and in the presence of activated charcoal (AC-BHI), respectively, relative to cells grown in BHI medium. Specifically, we show that metal ions present in BHI broth plays a role in the reduced expression of the PrfA regulon. In addition, we show that expression of hly is induced when the levels of bioavailable extra- or intercellular iron are reduced. L. monocytogenes cells grown Ch-BHI and AC-BHI media showed similar levels of resistance to the iron-activated antibiotic, streptonigrin, indicating that activated charcoal reduces the intracellular labile iron pool. Metal depletion and exogenously added glutathione contributed synergistically to PrfA-regulated gene expression since glutathione further increased hly expression in metal-depleted BHI but not in BHI medium. Analyses of transcriptional reporter fusion expression patterns revealed that genes in the PrfA regulon are differentially expressed in response to metal depletion, metal excess and exogenous glutathione. Our results suggest that metal ion abundance plays a role in modulating expression of PrfA-regulated virulence genes in L. monocytogenes.
Topics: Bacterial Proteins; Bacterial Toxins; Charcoal; Culture Media; Gene Expression Regulation, Bacterial; Glutathione; Heat-Shock Proteins; Hemolysin Proteins; Iron; Listeria monocytogenes; Peptide Termination Factors; Polystyrenes; Polyvinyls; Streptonigrin; Virulence; Zinc
PubMed: 33914817
DOI: 10.1371/journal.pone.0250989 -
Journal of Bacteriology Jun 2020Group A streptococcus (GAS) produces millions of infections worldwide, including mild mucosal infections, postinfection sequelae, and life-threatening invasive diseases....
Group A streptococcus (GAS) produces millions of infections worldwide, including mild mucosal infections, postinfection sequelae, and life-threatening invasive diseases. During infection, GAS readily acquires nutritional iron from host heme and hemoproteins. Here, we identified a new heme importer, named SiaFGH, and investigated its role in GAS pathophysiology. The SiaFGH proteins belong to a group of transporters with an unknown ligand from the recently described family of energy coupling factors (ECFs). A deletion mutant exhibited high streptonigrin resistance compared to the parental strain, suggesting that iron ions or an iron complex is the likely ligand. Iron uptake and inductively coupled plasma mass spectrometry (ICP-MS) studies showed that the loss of did not impact GAS import of ferric or ferrous iron, but the mutant was impaired in using hemoglobin iron for growth. Analysis of cells growing on hemoglobin iron revealed a substantial decrease in the cellular heme content in the mutant compared to the complemented strain. The induction of the genes in resulted in the induction of heme uptake. The mutant exhibited a significant impairment in murine models of mucosal colonization and systemic infection. Together, the data show that SiaFGH is a new type of heme importer that is key for GAS use of host hemoproteins and that this system is imperative for bacterial colonization and invasive infection. ECF systems are new transporters that take up various vitamins, cobalt, or nickel with a high affinity. Here, we establish the GAS SiaFGH proteins as a new ECF module that imports heme and demonstrate its importance in virulence. SiaFGH is the first heme ECF system described in bacteria. We identified homologous systems in the genomes of related pathogens from the phylum. Notably, GAS and other pathogens that use a SiaFGH-type importer rely on host hemoproteins for a source of iron during infection. Hence, recognizing the function of this noncanonical ABC transporter in heme acquisition and the critical role that it plays in disease has broad implications.
Topics: Animals; Bacterial Proteins; Biological Transport; Female; Gene Expression Regulation, Bacterial; Heme; Humans; Iron; Membrane Transport Proteins; Mice; Streptococcal Infections; Streptococcus pyogenes; Virulence
PubMed: 32393520
DOI: 10.1128/JB.00205-20 -
Bioorganic Chemistry Feb 2024Overexpression of transglutaminase 2 (TGase 2; TG2) has been implicated in the progression of renal cell carcinoma (RCC) through the inactivation of p53 by forming a...
Overexpression of transglutaminase 2 (TGase 2; TG2) has been implicated in the progression of renal cell carcinoma (RCC) through the inactivation of p53 by forming a protein complex. Because most p53 in RCC has no mutations, apoptosis can be increased by inhibiting the binding between TG2 and p53 to increase the stability of p53. In the present study, a novel TG2 inhibitor was discovered by investigating the structure of 1H-benzo[d]imidazole-4,7-dione as a simpler chemotype based on the amino-1,4-benzoquinone moiety of streptonigrin, a previously reported inhibitor. Through structure-activity relationship (SAR) studies, compound 8j (MD102) was discovered as a potent TG2 inhibitor with an IC value of 0.35 µM, p53 stabilization effect and anticancer effects in the ACHN and Caki-1 RCC cell lines with sulforhodamine B (SRB) GI values of 2.15 µM and 1.98 µM, respectively. The binding property of compound 8j (MD102) with TG2 was confirmed to be reversible in a competitive enzyme assay, and the binding interaction was expected to be formed at the β-sandwich domain, a p53 binding site, in the SPR binding assay with mutant proteins. The mode of binding of compound 8j (MD102) to the β-sandwich domain of TG2 was analyzed by molecular docking using the crystal structure of the active conformation of human TG2. Compound 8j (MD102) induced a decrease in the downstream signaling of p-AKT and p-mTOR through the stabilization of p53 by TG2 inhibition, resulting in tumor cell apoptosis. In a xenograft animal model using ACHN cancer cells, oral administration and intraperitoneal injection of compound 8j (MD102) showed an inhibitory effect on tumor growth, confirming increased levels of p53 and decreased levels of Ki-67 in tumor tissues through immunohistochemical (IHC) tissue staining. These results indicated that the inhibition of TG2 by compound 8j (MD102) could enhance p53 stabilization, thereby ultimately showing anticancer effects in RCC. Compound 8j (MD102), a novel TG2 inhibitor, can be further applied for the development of an anticancer candidate drug targeting RCC.
Topics: Animals; Humans; Antineoplastic Agents; Carcinoma, Renal Cell; Cell Line, Tumor; Imidazoles; Kidney Neoplasms; Molecular Docking Simulation; Protein Glutamine gamma Glutamyltransferase 2; Transglutaminases; Tumor Suppressor Protein p53
PubMed: 38154386
DOI: 10.1016/j.bioorg.2023.107061