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Background: Thermophilic Campylobacter are important bacterial pathogens of foodborne diseases worldwide. These organisms' physiology requires a microaerophilic atmosphere. To date, little is known about the protective catalase me...
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Background: Thermophilic Campylobacter are important bacterial pathogens of foodborne diseases worldwide. These organisms' physiology requires a microaerophilic atmosphere. To date, little is known about the protective catalase mechanism in urease-positive thermophilic campylobacters (UPTC); hence, it was the aim of this study to identify and characterise catalase and catalase-like protein genes in these organisms.Materials and methods: Catalase (katA) and catalase (Kat)-like protein genes from the Japanese UPTC CF89-12 strain were molecularly analysed and compared with C. lari RM2100 and other C. lari and thermophilic Campylobacter reference isolates.Results: A possible open reading frame of 1,422 base pairs, predicted to encode a peptide of 474 amino acid residues, with calculated molecular weight of 52.7 kilo Daltons for katA, was identified within UPTC CF89-12. A probable ribosome binding site, two putative promoters and a putative -independent transcription terminator were also identified within katA. A similar katA cluster also existed in the C. lari RM2100 strain, except that this strain carries no DcuB genes. However, the Kat-like protein gene or any other homologue(s) were never identified in the C. lari RM2100 strain, or in C. jejuni and C. upsaliensis.Conclusions: This study demonstrates the presence of catalase/catalase-like protein genes in UPTC organisms. These findings are significant in that they suggest that UPTC organisms have the protective genetic capability of helping protect the organisms from toxic oxygen stress, which may help them to survive in physiologically harsh environments, both within human and animal hosts, as well as in the natural environment.
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For efficient removal of intra- and/or extracellular hydrogen peroxide by dismutation to harmless dioxygen and water (2H _2O _2 → O _2 + 2H _2O), nature designed three metalloenzyme families that differ in oligomeric organization...
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For efficient removal of intra- and/or extracellular hydrogen peroxide by dismutation to harmless dioxygen and water (2H _2O _2 → O _2 + 2H _2O), nature designed three metalloenzyme families that differ in oligomeric organization, monomer architecture as well as active site geometry and catalytic residues. Here we report on the updated reconstruction of the molecular phylogeny of these three gene families. Ubiquitous typical (monofunctional) heme catalases are found in all domains of life showing a high structural conservation. Their evolution was directed from large subunit towards small subunit proteins and further to fused proteins where the catalase fold was retained but lost its original functionality. Bifunctional catalase-peroxidases were at the origin of one of the two main heme peroxidase superfamilies (i.e. peroxidase-catalase superfamily) and constitute a protein family predominantly present among eubacteria and archaea, but two evolutionary branches are also found in the eukaryotic world. Non-heme manganese catalases are a relatively small protein family with very old roots only present among bacteria and archaea. Phylogenetic analyses of the three protein families reveal features typical (i) for the evolution of whole genomes as well as (ii) for specific evolutionary events including horizontal gene transfer, paralog formation and gene fusion. As catalases have reached a striking diversity among prokaryotic and eukaryotic pathogens, understanding their phylogenetic and molecular relationship and function will contribute to drug design for prevention of diseases of humans, animals and plants.
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A monofunctional catalase and a bifunctional catalase-peroxidase were revealed by activity staining of nondenaturing PAGE in Frankia strain R43. Both enzymes were shown to be cytoplasmatic, growth regulated and expressed mainly du...
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A monofunctional catalase and a bifunctional catalase-peroxidase were revealed by activity staining of nondenaturing PAGE in Frankia strain R43. Both enzymes were shown to be cytoplasmatic, growth regulated and expressed mainly during the stationary growth phase. Nevertheless, low levels of constitutive expression could also be detected during the early stages of growth. Immunoblot analyses using a polyclonal antibody raised against a catalase-peroxidase purified from Streptomyces reticuli showed a band of 83.2 kDa, with the same growth dependent pattern as obtained by the non-denaturing PAGE analyses. Induction studies revealed that both enzymes were strongly induced by raising the intracellular concentration of H2O2 with paraquat, but not with exogenous H2O2. In addition, no acquisition of tolerance to exogenous H2O2 was observed whatever the pretreatment of the inocula, i.e. despite the expression level of both hydroperoxidases.
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Catalase-peroxidases represent one important subfamily of ancestral antioxidant enzymes originally evolved in bacteria for the protection against various forms of oxidative stress. KatG genes coding for these bifunctional catalase...
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Catalase-peroxidases represent one important subfamily of ancestral antioxidant enzymes originally evolved in bacteria for the protection against various forms of oxidative stress. KatG genes coding for these bifunctional catalase-peroxidases were during their peculiar evolution transferred from Bacteroidetes to the fungal phylum Ascomycota via a horizontal gene transfer event. Here we analyse a newly discovered fungal katG gene without introns coding for a thermostable catalase-peroxidase from Chaetomium thermophilum var. dissitum and compare it with closely related thermophilic and mesophilic katGs and their translation products. We show that CthediskatG gene resembling its bacterial counterparts has a typical eukaryotic transcription start site and also contains a conserved eukaryotic polyadenylation signal behind its 3' terminus. Moreover, we have detected polyA tails in corresponding transcripts of katG from two different mRNA libraries of C. thermophilum var. dis-stum Although otherwise highly conserved, only in katG genes of two C. thermophilum variants a unique 60 bp long deletion leading in the translated product with high probability to a modified loop and thus access to the prosthetic heme group was observed. We also present an updated molecular phylogeny revealing the evolutionary position of fungal thermostable catalase-peroxidases within a robust phylogenetic tree of the whole KatG subfamily.
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Pathogenic bacteria infections have posed a threat to human health worldwide. Nanomaterials with natural enzymatic activity provide an opportunity for the development of new antibacterial pathways. We successfully constructed iron...
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Pathogenic bacteria infections have posed a threat to human health worldwide. Nanomaterials with natural enzymatic activity provide an opportunity for the development of new antibacterial pathways. We successfully constructed iron phosphate nanozyme-hydrogel (FePO4-HG) with the traits of positive charge and macropores. Interestingly, FePO4-HG displayed not only peroxidase-like activity under acidic bacterial infectious microenvironment but also superoxide dismutase-catalase-like synergistic effects in neutral or weak alkaline conditions, thus protecting normal tissues from the peroxidase-like protocol with exogenous H2O2 damage. Furthermore, the positive charge and macropore structure of FePO4-HG could capture and restrict bacteria in the range of ROS destruction. Obviously, FePO4-HG exhibited excellent antibacterial ability against MRSA and AREC with the assistance of H2O2. Significantly, the FePO4-HG + H2O2 system could efficiently disrupt the bacterial biofilm formation and facilitate the glutathione oxidation process to rapid bacterial death with low cytotoxicity. Moreover, FePO4-HG was unsusceptible to bacterial resistance development in MRSA. Animal experiments showed that the FePO4-HG + H2O2 group could efficiently eliminate the MRSA infection and present excellent wound healing without inflammation and tissue adhesions. With further development and optimization, FePO4-HG has great potential as a new class of antibacterial agents to fight antibiotic-resistant pathogens.
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The emergence of multidrug-resistant tuberculosis has renewed interest in the study of drug resistance in mycobacteria with the objective of improved chemotherapy. The genetic basis of isoniazid resistance in a model mycobacterium...
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The emergence of multidrug-resistant tuberculosis has renewed interest in the study of drug resistance in mycobacteria with the objective of improved chemotherapy. The genetic basis of isoniazid resistance in a model mycobacterium was studied. Eleven isoniazid-resistant mutants of Mycobacterium smegmatis were created using transposon mutagenesis. Genetic and enzymatic characterisation of the mutants showed that katG, encoding T-catalase, was inactivated. The nucleotide sequence of M. smegmatis katG was determined and the mutation sites mapped demonstrating that both the amino and carboxyl halves of T-catalase an important for enzymatic activity. [References: 18]
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The preparation of two homoleptic manganese(II)complexes [Mn(4'R-ind)2] [ind is the anion of 1,3-bis(2-pyridylimino)isoindoline,R = H(1),Me(2)] is described.Both complexes have been structurally characterized by UV-Vis and IR spec...
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The preparation of two homoleptic manganese(II)complexes [Mn(4'R-ind)2] [ind is the anion of 1,3-bis(2-pyridylimino)isoindoline,R = H(1),Me(2)] is described.Both complexes have been structurally characterized by UV-Vis and IR spectroscopies.Crystallographic characterization of the [Mn(ind)2](1)complex has shown that the overall geometry around the six-coordinate manganese(II)ion is described as a slightly distorted octahedron in an N6 donor set.These complexes represent functional model systems for manganese catalases.
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New metal complexes of Co(II) and Cu(I) have been synthetized by reaction of metal salts with thiosemicarbazide (TSC: HL1) and urea (U). The metal complexes were characterized on the basis of elemental analyses, molar conductance,...
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New metal complexes of Co(II) and Cu(I) have been synthetized by reaction of metal salts with thiosemicarbazide (TSC: HL1) and urea (U). The metal complexes were characterized on the basis of elemental analyses, molar conductance, spectral (IR, H-1 NMR) studies, as well as thermogravimetric analysis. The spectral data show that in the complexes, only TSC is coordinated to the metal. The IR spectra of Co(II) and Cu(I) complexes are different. In addition to the bands of TSC, a new intense band at 2100 cm(-1) is assigned to the thiocyanate fragment produced in situ by the cleavage of the TSC C-N bond. On the basis of spectral studies, a N3O3 high-spin environment was assigned to [Co-(II)(L-1)(SCN)(H2O)(3)] complex and a dimeric form geometry for Cu(I) complex of general formula [Cu-(I)(HL1)(SCN)(H2O)]. In order to gain a better insight into the molecular structure and the reactivity of the ligand and its complexes, quantum chemical calculations were also performed to determine some electronic properties and geometric parameters of the ligand and Cu(I) and Co(II) complexes. The metal complexes have been tested for catalase-like activity in order to assess their catalytic properties. The results seem encouraging. The biological activity of the ligand and its metal complexes is evaluated as well.
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The doxorubicin-resistant, acute myelogenous leukemia cell line, AML-2/DX100, characterized by the over-expression of multidrug resistance protein (MRP) and the down-regulation of catalase, has advantages for the screening of MRP ...
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The doxorubicin-resistant, acute myelogenous leukemia cell line, AML-2/DX100, characterized by the over-expression of multidrug resistance protein (MRP) and the down-regulation of catalase, has advantages for the screening of MRP inhibitors as well as for cytotoxic substances producing potential reactive oxygen species. The screening power of AML-2/DX100 cells for an MRP inhibitor, probenecid, was approximately 4-fold stronger than that of another resistant cell line, HL-60/Adr, over-expressing MRP. AML-2/DX100 was approximately 2- to 5-fold more sensitive to pro-oxidants such as Paraquat, H2O2 and t-butyl hydroperoxide, when compared with its parental cells.
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Mononuclear complexes of N-methylpropanoate-N,N-bis-(2-pyridylmethyl)amine (MPBMPA) and N-propanoate-N,N-bis-(2-pyridylmethyl)amine (HPBMPA) with first row transition metals from Mn to Cu were synthesized and characterized by spec...
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Mononuclear complexes of N-methylpropanoate-N,N-bis-(2-pyridylmethyl)amine (MPBMPA) and N-propanoate-N,N-bis-(2-pyridylmethyl)amine (HPBMPA) with first row transition metals from Mn to Cu were synthesized and characterized by spectroscopy (infrared, UV-visible), electrochemistry (cyclic voltammetry), microanalysis and in four cases X-ray crystallography. Structure of the complexes revealed high flexibility of these ligands that can adopt facial (Fe) and meridional (Cu) geometry. Activity in the degradation of reactive oxygen species (superoxide radical anion: superoxide dismutase (SOD)-like activity and hydrogen peroxide: catalase-like activity) was tested throughout the complex series in aqueous solutions. In connection with the catalytic dismutation of H_2O_2, bleaching tests with morin were also conducted in water. Comparison of the two ligands helped in elucidating the possible role of the carboxylate moiety in the different catalytic reactions. Although no general trends could be revealed between reactivity and constitution of the first coordination sphere, plausible explanations for differences are discussed individually for SOD like, catalase-like and bleaching activity.
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