scholarly journals Activities of Alkyl Hydroperoxide Reductase Subunits C1 and C2 of Vibrio parahaemolyticus against Different Peroxides

2014 ◽  
Vol 80 (23) ◽  
pp. 7398-7404 ◽  
Author(s):  
Chun-Hui Chung ◽  
Tsung-yong Ma ◽  
Shin-yuan Fen ◽  
Hin-chung Wong
Keyword(s):  
Liquid Medium ◽  
Vibrio Parahaemolyticus ◽  
Vibrio Vulnificus ◽  
Incubation Temperature ◽  
Cumene Hydroperoxide ◽  
Organic Peroxides ◽  
Homologous Proteins ◽  
Alkyl Hydroperoxide Reductase ◽  
Content Type ◽  
Alkyl Hydroperoxide

ABSTRACTAlkyl hydroperoxide reductase subunit C gene (ahpC) functions were characterized inVibrio parahaemolyticus, a commonly occurring marine food-borne enteropathogenic bacterium. TwoahpCgenes,ahpC1(VPA1683) andahpC2(VP0580), encoded putative two-cysteine peroxiredoxins, which are highly similar to the homologous proteins ofVibrio vulnificus. The responses of deletion mutants ofahpCgenes to various peroxides were compared with and without gene complementation and at different incubation temperatures. The growth of theahpC1mutant andahpC1 ahpC2double mutant in liquid medium was significantly inhibited by organic peroxides, cumene hydroperoxide andtert-butyl hydroperoxide. However, inhibition was higher at 12°C and 22°C than at 37°C. Inhibiting effects were prevented by the complementaryahpC1gene. Inconsistent detoxification of H2O2byahpCgenes was demonstrated in an agar medium but not in a liquid medium. Complementation with anahpC2gene partially restored the peroxidase effect in the doubleahpC1 ahpC2mutant at 22°C. This investigation reveals thatahpC1is the chief peroxidase gene that acts against organic peroxides inV. parahaemolyticusand that the function of theahpCgenes is influenced by incubation temperature.

scholarly journals Roles of Alkyl Hydroperoxide Reductase Subunit C (AhpC) in Viable but Nonculturable Vibrio parahaemolyticus

2013 ◽  
Vol 79 (12) ◽  
pp. 3734-3743 ◽  
Author(s):  
Hen-Wei Wang ◽  
Chun-Hui Chung ◽  
Tsung-Yong Ma ◽  
Hin-chung Wong
Keyword(s):  
Vibrio Parahaemolyticus ◽  
Parent Strain ◽  
Vbnc State ◽  
Alkyl Hydroperoxide Reductase ◽  
Subunit C ◽  
Viable But Nonculturable ◽  
Content Type ◽  
Alkyl Hydroperoxide ◽  
The Times

ABSTRACTAlkyl hydroperoxide reductase subunit C (AhpC) is the catalytic subunit responsible for the detoxification of reactive oxygen species that form in bacterial cells or are derived from the host; thus, AhpC facilitates the survival of pathogenic bacteria under environmental stresses or during infection. This study investigates the role of AhpC in the induction and maintenance of a viable but nonculturable (VBNC) state inVibrio parahaemolyticus. In this investigation,ahpC1(VPA1683) andahpC2(VP0580) were identified in chromosomes II and I of this pathogen, respectively. Mutants with deletions of these twoahpCgenes and their complementary strains were constructed from the parent strain KX-V231. The growth of these strains was monitored on tryptic soy agar–3% NaCl in the presence of the extrinsic peroxides H2O2andtert-butyl hydroperoxide (t-BOOH) at different incubation temperatures. The results revealed that bothahpCgenes were protective againstt-BOOH, whileahpC1was protective against H2O2. The protective function ofahpC2at 4°C was higher than that ofahpC1. The times required to induce the VBNC state (4.7 weeks) at 4°C in a modified Morita mineral salt solution with 0.5% NaCl and then to maintain the VBNC state (4.7 weeks) in anahpC2mutant and anahpC1 ahpC2double mutant were significantly shorter than those for the parent strain (for induction, 6.2 weeks; for maintenance, 7.8 weeks) and theahpC1mutant (for induction, 6.0 weeks; for maintenance, 8.0 weeks) (P< 0.03). Complementation with anahpC2gene reversed the effects of theahpC2mutation in shortening the times for induction and maintenance of the VBNC state. This investigation identified the different functions of the twoahpCgenes and confirmed the particular role ofahpC2in the VBNC state ofV. parahaemolyticus.

scholarly journals Cold Shock Induces Chromosomal qnr in Vibrio Species and Plasmid-Mediated qnrS1 in Escherichia coli

2019 ◽  
Vol 63 (12) ◽  
Author(s):  
Hee-Chang Jang ◽  
Yin Wang ◽  
Chunhui Chen ◽  
Laura Vinué ◽  
George A. Jacoby ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Bacterial Community ◽  
Vibrio Parahaemolyticus ◽  
Cold Shock ◽  
Vibrio Vulnificus ◽  
Wild Type ◽  
Induced Expression ◽  
Content Type ◽  
E Coli ◽  
Dna Damaging Agents

ABSTRACT qnr genes are found in aquatic bacteria and were present in the bacterial community before the introduction of synthetic quinolones. Their natural functions are unknown. We evaluated expression of chromosomal qnr in Vibrio species in response to environmental stresses and DNA-damaging agents. Subinhibitory concentrations of quinolones, but not other DNA-damaging agents, increased expression of chromosomal qnr by more than five times in Vibrio parahaemolyticus, Vibrio vulnificus, and Vibrio mytili. Cold shock also induced expression of qnr in V. parahaemolyticus, V. vulnificus, and V. mytili, as well as expression of qnrS1 in Escherichia coli. qnrS1 induction by cold shock was not altered in ΔihfA or ΔihfB mutants or in a strain overexpressing dnaA, all of which otherwise directly modulate qnrS1 induction by ciprofloxacin. In contrast, the level of qnrS1 induction by cold shock was reduced in a ΔcspA mutant in the cold shock regulon compared to the wild type. In conclusion, cold shock and quinolones induce expression of chromosomal qnr in Vibrio species and of the related qnrS1 gene in E. coli.

scholarly journals PVv3, a New Shuttle Vector for Gene Expression in Vibrio vulnificus

2013 ◽  
Vol 80 (4) ◽  
pp. 1477-1481 ◽  
Author(s):  
Karina Klevanskaa ◽  
Nadja Bier ◽  
Kerstin Stingl ◽  
Eckhard Strauch ◽  
Stefan Hertwig
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Green Fluorescent Protein ◽  
Vibrio Parahaemolyticus ◽  
Fluorescent Protein ◽  
Vibrio Vulnificus ◽  
Shuttle Vector ◽  
Content Type ◽  
E Coli ◽  
Green Fluorescent

ABSTRACTAn efficient electroporation procedure forVibrio vulnificuswas designed using the new cloning vector pVv3 (3,107 bp). Transformation efficiencies up to 2 × 106transformants per μg DNA were achieved. The vector stably replicated in bothV. vulnificusandEscherichia coliand was also successfully introduced intoVibrio parahaemolyticusandVibrio cholerae. To demonstrate the suitability of the vector for molecular cloning, the green fluorescent protein (GFP) gene and thevvhBAhemolysin operon were inserted into the vector and functionally expressed inVibrioandE. coli.

Characterization of Organic Hydroperoxide Resistance Gene VPA1681 against Organic Peroxides in the Presence of Alkylhydroperoxide Reductase Genes in Vibrio parahaemolyticus

2021 ◽  
Author(s):  
Ning-Xin Chen ◽  
Ying-Jr Chu ◽  
Bin Ni ◽  
Paula Hsu ◽  
Hin-chung Wong
Keyword(s):  
Resistance Gene ◽  
Mutant Strain ◽  
Vibrio Parahaemolyticus ◽  
Reductase Activity ◽  
Cumene Hydroperoxide ◽  
Organic Peroxide ◽  
Reduced Form ◽  
Organic Peroxides ◽  
Organic Hydroperoxide ◽  
Mutant Strains

The marine foodborne enteropathogen Vibrio parahaemolyticus contains the chief organic peroxide reductases AphC1-AhpC2 and a putative organic hydroperoxide resistance enzyme (Ohr, VPA1681) against different peroxides. This study investigated the function of the Ohr under the presence of AhpC1-AhpC2 in this pathogen by gene mutation. Experimental results demonstrated that the ohr gene product was a weak scavenger of H 2 O 2 only in the mutant strains that lacked the peroxide sensor/regulator oxyR and ahpC1 - ahpC2 genes. The Ohr of V. parahaemolyticus was highly effective in scavenging organic peroxide, as demonstrated by assaying the defective changes in the △ ohr mutant strain and determining the detoxifying activity of the purified recombinant V. parahaemolyticus Ohr vp protein in the reduced form. The Ohr and AhpC1-AhpC2 exhibited similar functions against organic peroxides; however, only the △ ahpC1△ahpC2 mutant strain showed a significant increase in susceptibility to several disinfectants, organic acids, and antibiotics compared to the wild-type strain. The transcription of the ohr gene depended on exogenous cumene hydroperoxide (cumene) stress and was markedly enhanced in the △ ohrR (VPA1682) mutant strains. This study revealed the organic hydroperoxide reductase activity of the Ohr in V. parahaemolyticus , and its role probably depends on the sophisticated regulation by OhrR. IMPORTANCE Vibrio parahaemolyticus is the most prevalent foodborne pathogen in Taiwan and some other coastal Asian countries, and its antioxidative activity contributes to the tolerance of this bacterium to different environmental stresses. This study reports on the function of the organic hydroperoxide resistance gene ( ohr , VPA1681) and its gene regulator ohrR (VPA1682) in this pathogen. The strain with ohr gene was effective in protection against organic peroxide, and the recombinant Ohr vp was active in its reduced form. The function of Ohr was significant mostly in strains in which the function o f AhpC1-AhpC2 was limited. The ohrR repressor of the ohr gene was effective at low concentrations of organic peroxide. Other common Vibrio species contain homologous ohr , ohrR , ahpC1, and ahpC2 genes, which are phylogenetically close to those of V. parahaemolyticus may probably share similar functions to those revealed in this study.

scholarly journals Role of OxyR as a Peroxide-Sensing Positive Regulator in Streptomyces coelicolor A3(2)

2002 ◽  
Vol 184 (19) ◽  
pp. 5214-5222 ◽  
Author(s):  
Ji-Sook Hahn ◽  
So-Young Oh ◽  
Jung-Hye Roe
Keyword(s):  
Escherichia Coli ◽  
Streptomyces Coelicolor ◽  
Cumene Hydroperoxide ◽  
Exponential Phase ◽  
Alkyl Hydroperoxide Reductase ◽  
Direct Role ◽  
Positive Regulator ◽  
Alkyl Hydroperoxide ◽  
Serovar Typhimurium ◽  
Genes Encoding

ABSTRACT Genes encoding a homolog of Escherichia coli OxyR (oxyR) and an alkyl hydroperoxide reductase system (ahpC and ahpD) have been isolated from Streptomyces coelicolor A3(2). The ahpC and ahpD genes constitute an operon transcribed divergently from the oxyR gene. Expression of both ahpCD and oxyR genes was maximal at early exponential phase and decreased rapidly as cells entered mid-exponential phase. Overproduction of OxyR in Streptomyces lividans conferred resistance against cumene hydroperoxide and H2O2. The oxyR mutant produced fewer ahpCD and oxyR transcripts than the wild type, suggesting that OxyR acts as a positive regulator for their expression. Both oxyR and ahpCD transcripts increased more than fivefold within 10 min of H2O2 treatment and decreased to the normal level in 50 min, with kinetics similar to those of the CatR-mediated induction of the catalase A gene (catA) by H2O2. The oxyR mutant failed to induce oxyR and ahpCD genes in response to H2O2, indicating that OxyR is the modulator for the H2O2-dependent induction of these genes. Purified OxyR protein bound specifically to the intergenic region between ahpC and oxyR, suggesting its direct role in regulating these genes. These results demonstrate that in S. coelicolor OxyR mediates H2O2 induction of its own gene and genes for alkyl hydroperoxide reductase system, but not the catalase gene (catA), unlike in Escherichia coli and Salmonella enterica serovar Typhimurium.

scholarly journals Predatory Bacteria as Natural Modulators of Vibrio parahaemolyticus and Vibrio vulnificus in Seawater and Oysters

2012 ◽  
Vol 78 (20) ◽  
pp. 7455-7466 ◽  
Author(s):  
Gary P. Richards ◽  
Johnna P. Fay ◽  
Keyana A. Dickens ◽  
Michelle A. Parent ◽  
Douglas S. Soroka ◽  
...  
Keyword(s):  
Vibrio Parahaemolyticus ◽  
Vibrio Vulnificus ◽  
Regulatory Gene ◽  
Plaque Assay ◽  
Eastern Oyster ◽  
Host Cells ◽  
Natural Seawater ◽  
Content Type ◽  
Predatory Bacteria ◽  
Pathogenic Vibrios

ABSTRACTThis study shows that naturally occurringVibriopredatory bacteria (VPB) exert a major role in controlling pathogenic vibrios in seawater and shellfish. The growth and persistence ofVibrio parahaemolyticusandVibrio vulnificuswere assessed in natural seawater and in the Eastern oyster,Crassostrea virginica. The pathogens examined wereV. vulnificusstrain VV1003,V. parahaemolyticusO1:KUT (KUT stands for K untypeable), andV. parahaemolyticusO3:K6 and corresponding O3:K6 mutants deficient in thetoxRSvirulence regulatory gene or therpoSalternative stress response sigma factor gene. Vibrios were selected for streptomycin resistance, which facilitated their enumeration. In natural seawater, oysters bioconcentrated eachVibriostrain for 24 h at 22°C; however, counts rapidly declined to near negligible levels by 72 h. In natural seawater with or without oysters, vibrios decreased more than 3 log units to near negligible levels within 72 h. NeithertoxRSnorrpoShad a significant effect onVibriolevels. In autoclaved seawater,V. parahaemolyticusO3:K6 counts increased 1,000-fold over 72 h. Failure of the vibrios to persist in natural seawater and oysters led to screening of the water samples for VPB on lawns ofV. parahaemolyticusO3:K6 host cells. Many VPB, includingBdellovibrioand like organisms (BALOs;Bdellovibrio bacteriovorusandBacteriovorax stolpii) andMicavibrio aeruginosavorus-like predators, were detected by plaque assay and electron microscopic analysis of plaque-purified isolates from Atlantic, Gulf Coast, and Hawaiian seawater. WhenV. parahaemolyticusO3:K6 was added to natural seawater containing trace amounts of VPB,Vibriocounts diminished 3 log units to nondetectable levels, while VPB increased 3 log units within 48 h. We propose a new paradigm that VPB are important modulators of pathogenic vibrios in seawater and oysters.

scholarly journals Alkyl Hydroperoxide Reductase Is Required for Helicobacter cinaedi Intestinal Colonization and Survival under Oxidative Stress in BALB/c and BALB/c Interleukin-10−/−Mice

2011 ◽  
Vol 80 (3) ◽  
pp. 921-928 ◽  
Author(s):  
Nisanart Charoenlap ◽  
Zeli Shen ◽  
Megan E. McBee ◽  
Suresh Muthupalani ◽  
Gerald N. Wogan ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Serum Levels ◽  
Interleukin 10 ◽  
Intestinal Bacterium ◽  
Bacterial Survival ◽  
Alkyl Hydroperoxide Reductase ◽  
Content Type ◽  
Helicobacter Cinaedi ◽  
Alkyl Hydroperoxide

Helicobacter cinaedi, a common human intestinal bacterium, has been implicated in various enteric and systemic diseases in normal and immunocompromised patients. Protection against oxidative stress is a crucial component of bacterium-host interactions. Alkyl hydroperoxide reductase C (AhpC) is an enzyme responsible for detoxification of peroxides and is important in protection from peroxide-induced stress.H. cinaedipossesses a singleahpC, which was investigated with respect to its role in bacterial survival during oxidative stress. TheH. cinaedi ahpCmutant had diminished resistance to organic hydroperoxide toxicity but increased hydrogen peroxide resistance compared with the wild-type (WT) strain. The mutant also exhibited an oxygen-sensitive phenotype and was more susceptible to killing by macrophages than the WT strain.In vivoexperiments in BALB/c and BALB/c interleukin-10 (IL-10)−/−mice revealed that the cecal colonizing ability of theahpCmutant was significantly reduced. The mutant also had diminished ability to induce bacterium-specific immune responsesin vivo, as shown by immunoglobulin (IgG2a and IgG1) serum levels. Collectively, these data suggest thatH. cinaedi ahpCnot only contributes to protecting the organism against oxidative stress but also alters its pathogenic propertiesin vivo.

scholarly journals Functions of Two Types of NADH Oxidases in Energy Metabolism and Oxidative Stress of Streptococcus mutans

1999 ◽  
Vol 181 (19) ◽  
pp. 5940-5947 ◽  
Author(s):  
Masako Higuchi ◽  
Yuji Yamamoto ◽  
Leslie B. Poole ◽  
Mamoru Shimada ◽  
Yutaka Sato ◽  
...  
Keyword(s):  
Energy Metabolism ◽  
Streptococcus Mutans ◽  
Cumene Hydroperoxide ◽  
Alkyl Hydroperoxide Reductase ◽  
Reading Frame ◽  
Alkyl Hydroperoxide ◽  
Defective Mutant ◽  
Knockout Mutants ◽  
K 12

ABSTRACT We have previously identified two distinct NADH oxidases corresponding to H2O2-forming oxidase (Nox-1) and H2O-forming oxidase (Nox-2) induced inStreptococcus mutans. Sequence analyses indicated a strong similarity between Nox-1 and AhpF, the flavoprotein component ofSalmonella typhimurium alkyl hydroperoxide reductase; an open reading frame upstream of nox-1 also showed homology to AhpC, the direct peroxide-reducing component of S. typhimurium alkyl hydroperoxide reductase. To determine their physiological functions in S. mutans, we constructed knockout mutants of Nox-1, Nox-2, and/or the AhpC homologue; we verified that Nox-2 plays an important role in energy metabolism through the regeneration of NAD+ but Nox-1 contributes negligibly. The Nox-2 mutant exhibited greatly reduced aerobic growth on mannitol, whereas there was no significant effect of aerobiosis on the growth on mannitol of the other strains or growth on glucose of any of the strains. Although the Nox-2 mutants grew well on glucose aerobically, the end products of glucose fermentation by the Nox-2 mutant were substantially shifted to higher ratios of lactic acid to acetic acid compared with wild-type cells. The resistance to cumene hydroperoxide of Escherichia coli TA4315 (ahpCF-defective mutant) transformed with pAN119 containing both nox-1 and ahpC genes was not only restored but enhanced relative to that of E. coli K-12 (parent strain), indicating a clear function for Nox-1 as part of an alkyl hydroperoxide reductase system in vivo in combination with AhpC. Surprisingly, the Nox-1 and/or AhpC deficiency had no effect on the sensitivity of S. mutans to cumene hydroperoxide and H2O2, implying that the existence of some other antioxidant system(s) independent of Nox-1 in S. mutanscompensates for the deficiency.

scholarly journals Growth-Inhibitory Effect of D-Tryptophan onVibriospp. in Shucked and Live Oysters

2018 ◽  
Vol 84 (19) ◽  
Author(s):  
Jian Chen ◽  
Hiroko Kudo ◽  
Kaito Kan ◽  
Shuso Kawamura ◽  
Shige Koseki
Keyword(s):  
Growth Inhibition ◽  
Ambient Temperature ◽  
Vibrio Parahaemolyticus ◽  
Vibrio Vulnificus ◽  
Inhibitory Effect ◽  
Artificial Seawater ◽  
Growth Inhibitory Effect ◽  
Content Type ◽  
Growth Inhibitory ◽  
Salinity Levels

ABSTRACTVibrio vulnificusandVibrio parahaemolyticusare important human pathogens that are frequently transmitted via consumption of contaminated raw oysters. A small amount ofd-tryptophan (d-Trp) inhibits some foodborne pathogenic bacteria in high-salt environments. In this study, we aimed to evaluate the antibacterial effect ofd-Trp onV. vulnificusandV. parahaemolyticusin culture media, artificial seawater, and shucked and live oysters. The effectiveness ofd-Trp in growth inhibition ofVibriospp. was highly dependent on environmental NaCl concentrations. Higher levels of NaCl (>4.0%) withd-Trp (>20 mM) resulted in higher and more consistent growth inhibition of bothVibriospp. Treatment with 40 mMd-Trp significantly (P< 0.05) reduced viableV. parahaemolyticuscell counts in tryptic soy broth (TSB) with >4.0% NaCl at 25°C. In contrast,V. vulnificuswas more sensitive tod-Trp (20 mM) thanV. parahaemolyticus.d-Trp (40 mM) treatment with NaCl (>4.5%) significantly (P< 0.05) inhibited the growth ofV. parahaemolyticusandV. vulnificusin shucked oysters immersed in peptone water at 25°C throughout a 48-h incubation period. In artificial seawater,d-Trp exhibited a stronger growth-inhibitory effect onV. vulnificusandV. parahaemolyticusat 25°C than in TSB at the same level of salinity and inhibited the growth of bothV. parahaemolyticusandV. vulnificusin live oysters at 25°C for 48 h. Furthermore, we tested the synergistic effect ofd-Trp and salinity on the inhibition of total viable bacterial counts (TVC) at refrigeration temperature.d-Trp (40 mM) inhibited the growth of TVC in shucked oysters immersed in artificial seawater at 4°C. Therefore, these results revealed thatd-Trp will serve as a novel and alternative food preservative to controlVibriospp. in live oysters at ambient temperature and to extend the shelf-life of shucked oysters at refrigeration temperature.IMPORTANCEOysters are the primary transmission vehicles for humanVibrioinfections. Raw oyster consumption is frequently associated with gastroenteritis. The current postharvest methods, such as high-pressure processing, used to controlVibriospp. in fresh oysters are still insufficient because of limited facilities, high cost, and potential adverse effects on production. We demonstrate that adding a small amount ofd-tryptophan (d-Trp) inhibits the growths ofVibrio parahaemolyticusandVibrio vulnificusin a high-salt environment at even ambient temperature. We further investigated thed-Trp treatment conditions and clarified the relationship between salt andd-Trp concentrations for optimal growth-inhibitory effect ofVibriospp. The results will be useful for enhancing the effectiveness ofd-Trp by increasing salinity levels. Furthermore, in a nutrientfree environment (artificial seawater), a stronger inhibitory effect could be observed at relatively lower salinity levels, indicating thatd-Trp may be regarded as effective food preservation in terms of salinity reduction. Therefore, we suggest the use of exogenousd-Trp in a seawater environment as a novel and effective strategy not only for controllingVibrioin live oysters at even ambient temperature but also for effectively retarding spoilage bacterial growth and extending the shelf life of shucked oysters at refrigeration temperature.

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