Val43 residue of NsrR is crucial for the nitric oxide response of Typhimurium.

Abstract: In pathogenic bacteria, the flavohemoglobin Hmp is crucial in metabolizing the cytotoxic levels of nitric oxide (NO) produced in phagocytic cells, contributing to bacterial virulence. Hmp expression is predominantly regulated by the Rrf2 family transcription repressor NsrR in an NO-dependent manner; however, the underlying molecular mechanism in enterobacteria remains poorly understood. In this study, we identified Val43 of Typhimurium NsrR (StNsrR) as a critical amino acid residue for regulating Hmp expression.

Reliability of the In Silico Prediction Approach to In Vitro Evaluation of Bacterial Toxicity.

Several pathogens that spread through the air are highly contagious, and related infectious diseases are more easily transmitted through airborne transmission under indoor conditions, as observed during the COVID-19 pandemic. Indoor air contaminated by microorganisms, including viruses, bacteria, and fungi, or by derived pathogenic substances, can endanger human health. Thus, identifying and analyzing the potential pathogens residing in the air are crucial to preventing disease and maintaining indoor air quality.

Development of an Oral -Based Vaccine Platform against SARS-CoV-2.

Effective vaccine development for global outbreaks, such as the coronavirus disease 2019 (COVID-19), has been successful in the short run. However, the currently available vaccines have been associated with a higher frequency of adverse effects compared with other general vaccines. In this study, the possibility of an oral bacteria-based vaccine that can be safely used as a platform for large-scale, long-term immunization was evaluated.

SPME-GC/MS Analysis of Methanol in Biospecimen by Derivatization with Pyran Compound.

Methanol is metabolized in the body to highly toxic formaldehyde and formate when consumed accidentally. Methanol has been typically analyzed with gas chromatography-flame ionization detector (GC-FID). However, its retention time may overlap with other volatile compounds and lead to confusion.

The Small Protein CydX Is Required for Cytochrome Quinol Oxidase Stability and Function in Salmonella enterica Serovar Typhimurium: a Phenotypic Study.

Cytochrome quinol oxidases, which have a greater affinity for oxygen than heme-copper cytochrome oxidases (HCOs), promote bacterial respiration and fitness in low-oxygen environments, such as host tissues. Here, we show that, in addition to the CydA and CydB subunits, the small protein CydX is required for the assembly and function of the cytochrome complex in the enteric pathogen serovar Typhimurium. Mutant Typhimurium lacking CydX showed a loss of proper heme arrangement and impaired oxidase activity comparable to that of a Δ mutant lacking all cytochrome subunits.

Transcriptomic Identification and Biochemical Characterization of HmpA, a Nitric Oxide Dioxygenase, Essential for Pathogenesis of .

Nitric oxide (NO) and its derivatives are important effectors of host innate immunity, disrupting cellular function of infecting pathogens. Transcriptome analysis of , an opportunistic human pathogen, identified a set of genes induced upon exposure to NO. Among them, (), encoding a multidomain NO dioxygenase, was the most greatly induced upon exposure to NO and was thus further characterized.

Antimicrobial Mechanism of Oleanolic and Ursolic Acids on Streptococcus mutans UA159.

Triterpenoid saponin derivatives oleanolic acid (OA) and ursolic acid (UA), but not betulinic acid (BA), were previously found to have strong antimicrobial activity against Streptococcus mutans. OA and UA inhibited the transcription of genes related to peptidoglycan biosynthesis, thereby preventing bacterial growth. However, it is not clear whether this is the only pathway involved in the antimicrobial activity of these compounds against S.

Inducible Transcription Acts as a Sensor for Envelope Stress of .

infects a broad range of host animals, and zoonostic infection threatens both public health and the livestock and meat processing industries. Many antimicrobials have been developed to target envelope that performs essential bacterial functions; however, there are very few analytical methods that can be used to validate the efficacy of these antimicrobials. In this study, to develop a potential biosensor for envelope stress, we examined the transcription of the serovar gene, the ortholog of which in encodes Spy (spheroplast protein y).

Branched-chain amino acid supplementation promotes aerobic growth of Salmonella Typhimurium under nitrosative stress conditions.

Nitric oxide (NO) inactivates iron-sulfur enzymes in bacterial amino acid biosynthetic pathways, causing amino acid auxotrophy. We demonstrate that exogenous supplementation with branched-chain amino acids (BCAA) can restore the NO resistance of hmp mutant Salmonella Typhimurium lacking principal NO-metabolizing enzyme flavohemoglobin, and of mutants further lacking iron-sulfur enzymes dihydroxy-acid dehydratase (IlvD) and isopropylmalate isomerase (LeuCD) that are essential for BCAA biosynthesis, in an oxygen-dependent manner. BCAA supplementation did not affect the NO consumption rate of S.

The role of rpoS, hmp, and ssrAB in Salmonella enterica Gallinarum and evaluation of a triple-deletion mutant as a live vaccine candidate in Lohmann layer chickens.

Salmonella enterica Gallinarum (SG) causes fowl typhoid (FT), a septicemic disease in avian species. We constructed deletion mutants lacking the stress sigma factor RpoS, the nitric oxide (NO)-detoxifying flavohemoglobin Hmp, and the SsrA/SsrB regulator to confirm the functions of these factors in SG. All gene products were fully functional in wild-type (WT) SG whereas mutants harboring single mutations or a combination of rpoS, hmp, and ssrAB mutations showed hypersusceptibility to H2O2, loss of NO metabolism, and absence of Salmonella pathogenicity island (SPI)-2 expression, respectively.

Functional insight from the tetratricopeptide repeat-like motifs of the type III secretion chaperone SicA in Salmonella enterica serovar Typhimurium.

SicA functions both as a class II chaperone for SipB and SipC of the type III secretion system (T3SS)-1 and as a transcriptional cofactor for the AraC-type transcription factor InvF in Salmonella enterica subsp. enterica serovar Typhimurium. Bioinformatic analysis has predicted that SicA possesses three tetratricopeptide repeat (TPR)-like motifs, which are important for protein-protein interactions and serve as multiprotein complex mediators.

Enhancement of host immune responses by oral vaccination to Salmonella enterica serovar Typhimurium harboring both FliC and FljB flagella.

Flagellin, the structural component of the flagellar filament in various motile bacteria, can contribute to the activation of NF-κB and proinflammatory cytokine expression during the innate immune response in host cells. Thus, flagellin proteins represent a particularly attractive target for the development of vaccine candidates. In this study, we investigated the immune response by increasing the flagella number in the iacP mutant strain and the adjuvant activity of the flagellin component FljB of Salmonella enterica serovar Typhimurium.

Agr function is upregulated by photodynamic therapy for Staphylococcus aureus and is related to resistance to photodynamic therapy.

Photodynamic therapy (PDT) has been considered a feasible alternative for antimicrobial therapy of multidrug-resistant pathogens. However, bacterial response mechanisms against PDT-generated photo-oxidative stress remain largely unknown. Herein, it is shown that the accessory gene regulator Agr is involved in Staphylococcus aureus response to photo-oxidative stress generated by laser-induced PDT with the photosensitizer chlorin e6 .

Molecular characterization of the InvE regulator in the secretion of type III secretion translocases in Salmonella enterica serovar Typhimurium.

The type III secretion systems (T3SSs) are exploited by many Gram-negative pathogenic bacteria to deliver a set of effector proteins into the host cytosol during cell entry. The T3SS of Salmonella enterica serovar Typhimurium is composed of more than 20 proteins that constitute the membrane-associated base, the needle and the tip complex at the distal end of the T3SS needle. Membrane docking and piercing between the T3SS and host cells is followed by the secretion of effector proteins.

A phosphotransferase system permease is a novel component of CadC signaling in Salmonella enterica.

In Salmonella enterica serovar Typhimurium, proteolytic cleavage of the membrane-bound transcriptional regulator CadC acts as a switch to activate genes of the lysine decarboxylase system in response to low pH and lysine signals. To identify the genetic factors required for the proteolytic activation of CadC, we performed genome-wide random mutagenesis. We show that a phosphotransferase system (PTS) permease STM4538 acts as a positive modulator of CadC function.

Expression and delivery of tetanus toxin fragment C fused to the N-terminal domain of SipB enhances specific immune responses in mice.

Live attenuated bacteria can be used as a carrier for the delivery of foreign antigens to a host's immune system. The N-terminal domain of SipB, a translocon protein of the type III secretion system of Salmonella enterica serovar Typhimurium, is required for secretion and outer membrane localization. In the present study, vaccine plasmids for antigen delivery in which the non-toxic tetanus toxin fragment C (TTFC), which contains a T cell epitope, is fused to the N-terminal 160 amino acids of SipB were developed.

Effect of iacP mutation on flagellar phase variation in Salmonella enterica serovar typhimurium strain UK-1.

Flagella are surface appendages that are important for bacterial motility and invasion of host cells. Two flagellin subunits in Salmonella enterica serovar Typhimurium, FliC and FljB, are alternatively expressed by a site-specific DNA inversion mechanism called flagellar phase variation. Although this inversion mechanism is understood at the molecular level, the key factor controlling the expression of the two flagellin subunits has not been determined.

Nitrosative stress causes amino acid auxotrophy in hmp mutant Salmonella Typhimurium.

Cytotoxic nitic oxide (NO) damages various bacterial macromolecules, resulting in abnormal metabolism by mechanisms largely unknown. We show that NO can cause amino acid auxotrophy in Salmonella Typhimurium lacking major NO-metabolizing enzyme, flavohemoglobin Hmp. In NO-producing cultures, supplementation with amino acid pool restores growth of Hmp-deficient Salmonella to normal growth phases, whereas excluding Cys or BCAA Leu, Ile, or Val from amino acid pool reduces growth recovery.

Role of Salmonella Pathogenicity Island 1 protein IacP in Salmonella enterica serovar typhimurium pathogenesis.

Gram-negative bacteria, including Salmonella enterica serovar Typhimurium, exploit type III secretion systems (T3SSs) through which virulence proteins are delivered into the host cytosol to reinforce invasive and replicative niches in their host. Although many secreted effector proteins and membrane-bound structural proteins in the T3SS have been characterized, the functions of many cytoplasmic proteins still remain unknown. In this study, we found that IacP, encoded by Salmonella pathogenicity island 1, was important for nonphagocytic cell invasion and bacterial virulence.

Antimicrobial effect of photodynamic therapy using a highly pure chlorin e6.

The aim of the present study is to evaluate the antimicrobial effect of photodynamic therapy (PDT) using a highly pure chlorin e(6) (Ce(6)), against various pathogenic bacteria. To examine the antimicrobial effect of Ce(6)-mediated PDT against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Salmonella enterica serovar Typhimurium, inhibition zone formation, CFU quantification, and bacterial viability were evaluated. Inhibition zone analysis showed that Ce(6)-mediated PDT is very effective to inhibit the growth of S.

Acid stress activation of the sigma(E) stress response in Salmonella enterica serovar Typhimurium.

The alternative sigma factor sigma(E) is activated by unfolded outer membrane proteins (OMPs) and plays an essential role in Salmonella pathogenesis. The canonical pathway of sigma(E) activation in response to envelope stress involves sequential proteolysis of the anti-sigma factor RseA by the PDZ proteases DegS and RseP. Here we show that sigma(E) in Salmonella enterica sv.

A 60-Hz sinusoidal magnetic field induces apoptosis of prostate cancer cells through reactive oxygen species.

Purpose: To explore the effects of power frequency magnetic fields (MF) on cell growth in prostate cancer, DU145, PC3, and LNCaP cells were examined in vitro.

Materials And Methods: The cells were exposed to various intensities and durations of 60-Hz sinusoidal MF in combination with various serum concentrations in the media. To analyze MF effects on cell growth, cell counting, trypan blue exclusion assay, Western blot analysis, flow cytometry, enzyme-linked immunosorbent assay (ELISA), semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR), fluorescence microscopy, and spectrofluorometry were used.

The membrane-bound transcriptional regulator CadC is activated by proteolytic cleavage in response to acid stress.

Proteolytic processes often participate in signal transduction across bacterial membranes. In Salmonella enterica serovar Typhimurium, the transcriptional regulator CadC activates genes of lysine decarboxylase system in response to external acidification and exogenous lysine. However, the signaling mechanism of CadC activation remains unexplored.

N-terminal residues of SipB are required for its surface localization on Salmonella enterica serovar Typhimurium.

SipB, one of the invasion proteins encoded in Salmonella pathogenicity island 1 (SPI-1), is known to be secreted outside the cell, where it functions as a translocon by assembling into a host-cell plasma membrane-integral structure. Here, we confirmed that wild-type SipB could be localized to the bacterial outer membrane, and further showed that its localization was dependent on extracellular secretion, and was independent of the presence of the SipD protein. Proteinase K susceptibility and immunofluorescence assays indicated that SipB was not incorporated into the outer membrane, but rather was displayed on the bacterial surface.