scholarly journals Role of Alkyl Hydroperoxide Reductase (AhpC) in the Biofilm Formation of Campylobacter jejuni

PLoS ONE ◽  
2014 ◽  
Vol 9 (1) ◽  
pp. e87312 ◽  
Author(s):  
Euna Oh ◽  
Byeonghwa Jeon
Keyword(s):  
Campylobacter Jejuni ◽  
Biofilm Formation ◽  
Alkyl Hydroperoxide Reductase ◽  
Alkyl Hydroperoxide

scholarly journals Role of the Alkyl Hydroperoxide Reductase (ahpCF) Gene in Oxidative Stress Defense of the Obligate Anaerobe Bacteroides fragilis

1999 ◽  
Vol 181 (18) ◽  
pp. 5701-5710 ◽  
Author(s):  
Edson R. Rocha ◽  
C. Jeffrey Smith
Keyword(s):  
Fusidic Acid ◽  
Resistant Strain ◽  
Parent Strain ◽  
Bacteroides Fragilis ◽  
Northern Blot Hybridization ◽  
Obligate Anaerobe ◽  
Alkyl Hydroperoxide Reductase ◽  
Oxygen Exposure ◽  
Alkyl Hydroperoxide

ABSTRACT In this study we report the identification and role of the alkyl hydroperoxide reductase (ahp) gene in Bacteroides fragilis. The two components of ahp,ahpC, and ahpF, are organized in an operon, and the deduced amino acid sequences revealed that B. fragilisAhpCF shares approximately 60% identity to orthologues in other gram-positive and gram-negative bacteria. Northern blot hybridization analysis of total RNA showed that the ahpCF genes were transcribed as a polycistronic 2.4-kb mRNA and that ahpCalso was present as a 0.6-kb monocistronic mRNA. ahpC andahpCF mRNAs were induced approximately 60-fold following H2O2 treatment or oxygen exposure of the parent strain but were constitutive in a peroxide-resistant strain. Further investigation using an ahpCF′::β-xylosidase gene transcriptional fusion confirmed that ahpCF had lost normal regulation in the peroxide-resistant strain compared to the parent. The ahpCF mutant was more sensitive to growth inhibition and mutagenesis by organic peroxides than the parent strain, as determined by disk inhibition assays and the frequency of mutation to fusidic acid resistance. This finding suggests that theahp genes play an important role in peroxide resistance inB. fragilis. Under anaerobic conditions, we observed increases in the number of spontaneous fusidic acid-resistant mutants of five- and sevenfold in ahpCF and ahpF strain backgrounds, respectively, and eightfold in the ahpCF katBdouble mutant strain compared to the parent and katBstrains. In addition, ahpCF, ahpF, andahpCF katB mutants were slightly more sensitive to oxygen exposure than the parent strain. Moreover, the isolation of a strain with enhanced aerotolerance and high-level resistance to alkyl hydroperoxides from an ahpCF katB parent suggests that the physiological responses to peroxide toxicity and to the toxic effects of molecular oxygen are overlapping and complex in this obligate anaerobe.

scholarly journals An Iron-Regulated Alkyl Hydroperoxide Reductase (AhpC) Confers Aerotolerance and Oxidative Stress Resistance to the Microaerophilic Pathogen Campylobacter jejuni

1999 ◽  
Vol 181 (16) ◽  
pp. 4798-4804 ◽  
Author(s):  
Marie-Louise A. Baillon ◽  
Arnoud H. M. van Vliet ◽  
Julian M. Ketley ◽  
Chrystala Constantinidou ◽  
Charles W. Penn
Keyword(s):  
Oxidative Stress ◽  
Campylobacter Jejuni ◽  
Insertional Mutagenesis ◽  
Atmospheric Oxygen ◽  
Large Subunit ◽  
Upstream Region ◽  
Transcriptional Level ◽  
Alkyl Hydroperoxide Reductase ◽  
Oxidative Stresses ◽  
Alkyl Hydroperoxide

ABSTRACT Microaerophiles like Campylobacter jejuni must resist oxidative stresses during transmission or infection. Growth of C. jejuni 81116 under iron limitation greatly increased the expression of two polypeptides of 26 and 55 kDa. The identification of these proteins by N-terminal amino acid sequencing showed both to be involved in the defense against oxidative stress. The 55-kDa polypeptide was identical to C. jejuni catalase (KatA), whereas the N terminus of the 26-kDa polypeptide was homologous to a 26-kDa Helicobacter pylori protein. The gene encoding theC. jejuni 26-kDa protein was cloned, and the encoded protein showed significant homology to the small subunit of alkyl hydroperoxide reductase (AhpC). The upstream region of ahpCencoded a divergent ferredoxin (fdxA) homolog, whereas downstream sequences contained flhB and motBhomologs, which are involved in flagellar motility. There was no evidence for an adjacent homolog of ahpF, encoding the large subunit of alkyl hydroperoxide reductase. Reporter gene studies showed that iron regulation of ahpC and katA is achieved at the transcriptional level. Insertional mutagenesis of theahpC gene resulted in an increased sensitivity to oxidative stresses caused by cumene hydroperoxide and exposure to atmospheric oxygen, while resistance to hydrogen peroxide was not affected. TheC. jejuni AhpC protein is an important determinant of the ability of this microaerophilic pathogen to survive oxidative and aerobic stress.

scholarly journals Effects of Sequential Campylobacter jejuni 81-176 Lipooligosaccharide Core Truncations on Biofilm Formation, Stress Survival, and Pathogenesis

2010 ◽  
Vol 192 (8) ◽  
pp. 2182-2192 ◽  
Author(s):  
Mizue Naito ◽  
Emilisa Frirdich ◽  
Joshua A. Fields ◽  
Mark Pryjma ◽  
Jianjun Li ◽  
...  
Keyword(s):  
Campylobacter Jejuni ◽  
Biofilm Formation ◽  
Cell Envelope ◽  
Polymyxin B ◽  
Outer Core ◽  
Survival Strategies ◽  
Calcofluor White ◽  
Stress Survival ◽  
Insight Into

ABSTRACTCampylobacter jejuniis a highly prevalent human pathogen for which pathogenic and stress survival strategies remain relatively poorly understood. We previously found that aC. jejunistrain 81-176 mutant defective for key virulence and stress survival attributes was also hyper-biofilm and hyperreactive to the UV fluorescent dye calcofluor white (CFW). We hypothesized that screening for CFW hyperreactive mutants would identify additional genes required forC. jejunipathogenesis properties. Surprisingly, two such mutants harbored lesions in lipooligosaccharide (LOS) genes (waaFandlgtF), indicating a complete loss of the LOS outer core region. We utilized this as an opportunity to explore the role of each LOS core-specific moiety in the pathogenesis and stress survival of this strain and thus also constructed ΔgalTand ΔcstIImutants with more minor LOS truncations. Interestingly, we found that mutants lacking the LOS outer core (ΔwaaFand ΔlgtFbut not ΔgalTor ΔcstIImutants) exhibited enhanced biofilm formation. The presence of the complete outer core was also necessary for resistance to complement-mediated killing. In contrast, any LOS truncation, even that of the terminal sialic acid (ΔcstII), resulted in diminished resistance to polymyxin B. The cathelicidin LL-37 was found to be active againstC. jejuni, with the LOS mutants exhibiting modest but tiled alterations in LL-37 sensitivity. The ΔwaaFmutant but not the other LOS mutant strains also exhibited a defect in intraepithelial cell survival, an aspect ofC. jejunipathogenesis that has only recently begun to be clarified. Finally, using a mouse competition model, we now provide the first direct evidence for the importance of theC. jejuniLOS in host colonization. Collectively, this study has uncovered novel roles for theC. jejuniLOS, highlights the dynamic nature of theC. jejunicell envelope, and provides insight into the contribution of specific LOS core moieties to stress survival and pathogenesis.

scholarly journals Mutagenic strategies against luxS gene affect the early stage of biofilm formation of Campylobacter jejuni

2021 ◽  
Author(s):  
Martin Tereň ◽  
Ekaterina Shagieva ◽  
Lucie Vondrakova ◽  
Jitka Viktorova ◽  
Viviana Svarcova ◽  
...  
Keyword(s):  
Campylobacter Jejuni ◽  
Biofilm Formation ◽  
Early Stage ◽  
Wild Type ◽  
Genetic Determinants ◽  
Autoinducer 2 ◽  
Naturally Occurring ◽  
Mutant Strains ◽  
The Impact

Abstract Currently, it is clear that the luxS gene has an impact on the process of biofilm formation in Campylobacter jejuni. However, even within the species naturally occurring strains of Campylobacter lacking the luxS gene exist, which can form biofilms. In order to better understand the genetic determinants and the role of quorum sensing through the LuxS/AI-2 pathway in biofilm formation, a set of mutant/complemented strains of C. jejuni 81–176 were prepared. Additionally, the impact of the mutagenic strategy used against the luxS gene was investigated. Biofilm formation was affected by both the presence and absence of the luxS gene, and by the mutagenic strategy used. Analysis by CLSM showed that all mutant strains formed significantly less biofilm mass when compared to the wild-type. Interestingly, the deletion mutant (∆luxS) showed a larger decrease in biofilm mass than the substitution (∙luxS) and insertional inactivated (⸬luxS) mutants, even though all the mutant strains lost the ability to produce autoinducer-2 molecules. Moreover, the biofilm of the ∆luxS mutant lacked the characteristic microcolonies observed in all other strains. The complementation of all mutant strains resulted in restored ability to produce AI-2, to form a complex biofilm, and to develop microcolonies at the level of the wild-type.

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.

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