scholarly journals KatG Is the Primary Detoxifier of Hydrogen Peroxide Produced by Aerobic Metabolism in Bradyrhizobium japonicum

2004 ◽  
Vol 186 (23) ◽  
pp. 7874-7880 ◽  
Author(s):  
Heather R. Panek ◽  
Mark R. O'Brian
Keyword(s):  
Catalase Activity ◽  
Bradyrhizobium Japonicum ◽  
Aerobic Metabolism ◽  
Short Exposure ◽  
Wild Type ◽  
Gene Encoding ◽  
Whole Cells ◽  
Cell Extracts ◽  
Genes Encoding ◽  
High Concentrations

ABSTRACT Bacteria are exposed to reactive oxygen species from the environment and from those generated by aerobic metabolism. Catalases are heme proteins that detoxify H2O2, and many bacteria contain more than one catalase enzyme. Also, the nonheme peroxidase alkyl hydroperoxide reductase (Ahp) is the major scavenger of endogenous H2O2 in Escherichia coli. Here, we show that aerobically grown Bradyrhizobium japonicum cells express a single catalase activity. Four genes encoding putative catalases in the B. japonicum genome were identified, including a katG homolog encoding a catalase-peroxidase. Deletion of the katG gene resulted in loss of catalase activity in cell extracts and of exogenous H2O2 consumption by whole cells. The katG strain had a severe aerobic growth phenotype but showed improved growth in the absence of O2. By contrast, a B. japonicum ahpCD mutant grew well aerobically and consumed H2O2 at wild-type rates. A heme-deficient hemA mutant expressed about one-third of the KatG activity as the wild type but grew well aerobically and scavenged low concentrations of exogenous H2O2. However, cells of the hemA strain were deficient in consumption of high concentrations of H2O2 and were very sensitive to killing by short exposure to H2O2. In addition, KatG activity did not decrease as a result of mutation of the gene encoding the transcriptional activator OxyR. We conclude that aerobic metabolism produces toxic levels of H2O2 in B. japonicum, which is detoxified primarily by KatG. Furthermore, the katG level sufficient for detoxification does not require OxyR.

scholarly journals Sialylation of Lipooligosaccharide Cores Affects Immunogenicity and Serum Resistance of Campylobacter jejuni

2000 ◽  
Vol 68 (12) ◽  
pp. 6656-6662 ◽  
Author(s):  
Patricia Guerry ◽  
Cheryl P. Ewing ◽  
Thomas E. Hickey ◽  
Martina M. Prendergast ◽  
Anthony P. Moran
Keyword(s):  
Electrophoretic Mobility ◽  
Campylobacter Jejuni ◽  
Polyclonal Antiserum ◽  
Wild Type ◽  
Gene Encoding ◽  
Whole Cells ◽  
Acetylneuraminic Acid ◽  
Genes Encoding ◽  
Hyperimmune Antiserum ◽  
Human Sera

ABSTRACT Three genes involved in biosynthesis of the lipooligosaccharide (LOS) core of Campylobacter jejuni MSC57360, the type strain of the HS:1 serotype, whose structure mimics GM2ganglioside, have been cloned and characterized. Mutation of genes encoding proteins with homology to a sialyl transferase (cstII) and a putative N-acetylmannosamine synthetase (neuC1), part of the biosynthetic pathway ofN-acetylneuraminic acid (NeuNAc), have identical phenotypes. The LOS cores of these mutants display identical changes in electrophoretic mobility, loss of reactivity with cholera toxin (CT), and enhanced immunoreactivity with a hyperimmune polyclonal antiserum generated against whole cells of C. jejuni MSC57360. Loss of sialic acid in the core of the neuC1 mutant was confirmed by fast atom bombardment mass spectrometry. Mutation of a gene encoding a putative β-1,4-N-acetylgalactosaminyltransferase (Cgt) resulted in LOS cores intermediate in electrophoretic mobility between that of wild type and the mutants lacking NeuNAc, loss of reactivity with CT, and a reduced immunoreactivity with hyperimmune antiserum. Chemical analyses confirmed the loss of N-acetylgalactosamine (GalNAc) and the presence of NeuNAc in the cgt mutant. These data suggest that the Cgt enzyme is capable of transferring GalNAc to an acceptor with or without NeuNAc and that the Cst enzyme is capable of transferring NeuNAc to an acceptor with or without GalNAc. A mutant with a nonsialylated LOS core is more sensitive to the bactericidal effects of human sera than the wild type or the mutant lacking GalNAc.

scholarly journals Expression and function of the cdgD gene, encoding a CHASE–PAS-DGC-EAL domain protein, in Azospirillum brasilense

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
José Francisco Cruz-Pérez ◽  
Roxana Lara-Oueilhe ◽  
Cynthia Marcos-Jiménez ◽  
Ricardo Cuatlayotl-Olarte ◽  
María Luisa Xiqui-Vázquez ◽  
...  
Keyword(s):  
Azospirillum Brasilense ◽  
Type Strain ◽  
Wild Type Strain ◽  
Soil Conditions ◽  
Wild Type ◽  
Gene Encoding ◽  
Wheat Roots ◽  
Genes Encoding ◽  
In The Wild ◽  
Plant Growth Promoting

AbstractThe plant growth-promoting bacterium Azospirillum brasilense contains several genes encoding proteins involved in the biosynthesis and degradation of the second messenger cyclic-di-GMP, which may control key bacterial functions, such as biofilm formation and motility. Here, we analysed the function and expression of the cdgD gene, encoding a multidomain protein that includes GGDEF-EAL domains and CHASE and PAS domains. An insertional cdgD gene mutant was constructed, and analysis of biofilm and extracellular polymeric substance production, as well as the motility phenotype indicated that cdgD encoded a functional diguanylate protein. These results were correlated with a reduced overall cellular concentration of cyclic-di-GMP in the mutant over 48 h compared with that observed in the wild-type strain, which was recovered in the complemented strain. In addition, cdgD gene expression was measured in cells growing under planktonic or biofilm conditions, and differential expression was observed when KNO3 or NH4Cl was added to the minimal medium as a nitrogen source. The transcriptional fusion of the cdgD promoter with the gene encoding the autofluorescent mCherry protein indicated that the cdgD gene was expressed both under abiotic conditions and in association with wheat roots. Reduced colonization of wheat roots was observed for the mutant compared with the wild-type strain grown in the same soil conditions. The Azospirillum-plant association begins with the motility of the bacterium towards the plant rhizosphere followed by the adsorption and adherence of these bacteria to plant roots. Therefore, it is important to study the genes that contribute to this initial interaction of the bacterium with its host plant.

scholarly journals Analysis of Cytadherence-Deficient, GapA-NegativeMycoplasma gallisepticum Strain R

2000 ◽  
Vol 68 (12) ◽  
pp. 6643-6649 ◽  
Author(s):  
L. Papazisi ◽  
K. E. Troy ◽  
T. S. Gorton ◽  
X. Liao ◽  
S. J. Geary
Keyword(s):  
Shuttle Vector ◽  
Phenotypic Expression ◽  
Mycoplasma Genitalium ◽  
Transcriptional Analysis ◽  
Start Codon ◽  
Wild Type ◽  
Gene Encoding ◽  
Genes Encoding ◽  
Low Passage ◽  
Translational Start

ABSTRACT Comparison of the phenotypic expression of Mycoplasma gallisepticum strain R low (passage 15) to that of strain R high (passage 164) revealed that three proteins, i.e., the cytadhesin molecule GapA, a 116-kDa protein (p116), and a 45-kDa protein (p45), are missing in strain R high. Sequence analysis confirmed that the insertion of an adenine 105 bp downstream of the gapAtranslational start codon resulted in premature termination of translation in R high. A second adenine insertion had also occurred at position 907. Restoration of expression of wild-type gapAin R high (clone designated GT5) allowed us to evaluate the extent to which the diminished cytadherence capacity could be attributed to GapA alone. The results indicated that GT5 attached to the same limited extent as the parental R high, from which it was derived. The cytadherence capability of the parental R high was not restored solely by gapA complementation alone, indicating that either p116 or p45 or both may play a role in the overall cytadherence process. The gene encoding p116 was found to be immediately downstream ofgapA in the same operon and was designatedcrmA. This gene exhibited striking homology to genes encoding molecules with cytadhesin-related functions in bothMycoplasma pneumoniae and Mycoplasma genitalium. Transcriptional analysis revealed thatcrmA is not transcribed in R high. We are currently constructing a shuttle vector containing both the wild-typegapA and crmA for transformation into R high to assess the role of CrmA in the cytadherence process.

Catalase activity in Campylobacter jejuni: comparison of a wild-type strain with an aerotolerant variant

1990 ◽  
Vol 36 (6) ◽  
pp. 449-451 ◽  
Author(s):  
Pamela A. Vercellone ◽  
Robert M. Smibert ◽  
Noel R. Krieg
Keyword(s):  
Campylobacter Jejuni ◽  
Catalase Activity ◽  
Specific Activity ◽  
Wild Type ◽  
Oxygen Tolerance ◽  
Variant Strain ◽  
Cultural Conditions ◽  
Cell Extracts ◽  
Bactericidal Effects

A comparison of Campylobacter jejuni VPI strain H840 (ATCC 29428), which can grow at O2 levels up to 15%, with variant strain MC711-01 (which can grown at O2 levels up to 21–26%) indicated that the specific activity of catalase in crude cell extracts was higher in the variant by a factor of 1.6 to 2.5, depending on cultural conditions. Smaller differences occurred with superoxide dismutase activity, while peroxidase activities were invariably lower in the variant strain. The variant strain was much more resistant than the wild type to the bactericidal effects of H2O2. The results suggest that catalase activity might be one of the factors associated with the greater tolerance of O2 by the variant strain. However, both strains became more susceptible to H2O2 when cultures were initially grown at 6% O2 and then shifted to 21% O2; thus the role of catalase in the oxygen tolerance of C. jejuni is probably minor. Key words: Campylobacter jejuni, catalase, oxygen tolerance.

Catalase activity and the survival of Pseudomonas putida, a root colonizer, upon treatment with peracetic acid

2001 ◽  
Vol 47 (3) ◽  
pp. 222-228 ◽  
Author(s):  
Anne J Anderson ◽  
Charles D Miller
Keyword(s):  
Hydrogen Peroxide ◽  
Pseudomonas Putida ◽  
Peracetic Acid ◽  
Catalase Activity ◽  
Specific Activity ◽  
Active Oxygen Species ◽  
Oxygen Species ◽  
Deficient Mutant ◽  
Wild Type ◽  
Cell Extracts

Peracetic acid is used as a sterilant in several industrial settings. Cells of a plant-colonizing bacterium, Pseudomonas putida in liquid suspension, were more sensitive to killing by peracetic acid when they lacked a major catalase activity, catalase A. Low doses of peracetic acid induced promoter activity of the gene encoding catalase A and increased total catalase specific activity in cell extracts. Microbes present in native agricultural soils rapidly degraded the active oxygen species present in peracetic acid. The simultaneous release of oxygen was consistent with a role for catalase in degrading the hydrogen peroxide that is part of the peracetic acid-equilibrium mixture. Amendment of sterilized soils with wild-type P. putida restored the rate of degradation of peracetic acid to a higher level than was observed in the soils amended with the catalase A-deficient mutant. The association of the bacteria with the plant roots resulted in protection of the wild-type as well as the catalase-deficient mutant from killing by peracetic acid. No differential recovery of the wild-type and catalase A mutant of P. putida was observed from roots after the growth matrix containing the plants was flushed with peracetic acid.Key words: Pseudomonas putida (Pp), activated oxygen species (AOS), hydrogen peroxide, luciferase, colonization.

The role of catalase in hydrogen peroxide resistance in fission yeast Schizosaccharomyces pombe

1999 ◽  
Vol 45 (2) ◽  
pp. 125-129 ◽  
Author(s):  
Norihiro Mutoh ◽  
Chiaki W Nakagawa ◽  
Kenichiro Yamada
Keyword(s):  
Hydrogen Peroxide ◽  
Schizosaccharomyces Pombe ◽  
Catalase Activity ◽  
Parent Strain ◽  
Normal Growth ◽  
Wild Type ◽  
Catalase Gene ◽  
In The Wild ◽  
High Concentrations

The role of catalase in hydrogen peroxide resistance in Schizosaccharomyces pombe was investigated. A catalase gene disruptant completely lacking catalase activity is more sensitive to hydrogen peroxide than the parent strain. The mutant does not acquire hydrogen peroxide resistance by osmotic stress, a treatment that induces catalase activity in the wild-type cells. The growth rate of the disruptant is not different from that of the parent strain. Additionally, transformed cells that overexpress the catalase activity are more resistant to hydrogen peroxide than wild-type cells with normal catalase activity. These results indicate that the catalase of S. pombe plays an important role in resistance to high concentrations of hydrogen peroxide but offers little in the way of protection from the hydrogen peroxide generated in small amounts under normal growth conditions.Key words: catalase, gene disruption, induced hydrogen peroxide resistance, overexpression, Schizosaccharomyces pombe.

scholarly journals Mmp10 is required for post-translational methylation of arginine at the active site of methyl-coenzyme M reductase

2017 ◽  
Author(s):  
Zhe Lyu ◽  
Chau-wen Chou ◽  
Hao Shi ◽  
Ricky Patel ◽  
Evert C. Duin ◽  
...  
Keyword(s):  
Active Site ◽  
Methane Formation ◽  
Wild Type ◽  
Coenzyme M ◽  
Methane Cycle ◽  
Gene Encoding ◽  
Post Translational Modifications ◽  
Whole Cells ◽  
Type Gene ◽  
Methyl Coenzyme M Reductase

AbstractCatalyzing the key step for anaerobic methane production and oxidation, methyl-coenzyme M reductase or Mcr plays a key role in the global methane cycle. The McrA subunit possesses up to five post-translational modifications (PTM) at its active site. Bioinformatic analyses had previously suggested that methanogenesis marker protein 10 (Mmp10) could play an important role in methanogenesis. To examine its role, MMP1554, the gene encoding Mmp10 inMethanococcus maripaludis, was deleted with a new genetic tool, resulting in the specific loss of the 5-(S)-methylarginine PTM of residue 275 in the McrA subunit and a 40~60 % reduction in the maximal rates of methane formation by whole cells. Methylation was restored by complementations with the wild-type gene. However, the rates of methane formation of the complemented strains were not always restored to the wild type level. This study demonstrates the importance of Mmp10 and the methyl-Arg PTM on Mcr activity.

A Mechanism of Resistance to Hydrogen Peroxide inVibrio rumoiensis S-1

1999 ◽  
Vol 65 (1) ◽  
pp. 73-79 ◽  
Author(s):  
Nobutoshi Ichise ◽  
Naoki Morita ◽  
Tamotsu Hoshino ◽  
Kosei Kawasaki ◽  
Isao Yumoto ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Catalase Activity ◽  
Processing Plant ◽  
Spontaneous Mutant ◽  
Gene Encoding ◽  
E Coli ◽  
Mechanism Of Resistance ◽  
High Concentrations ◽  
Almost All ◽  
Very High

ABSTRACT A possible mechanism of resistance to hydrogen peroxide (H2O2) in Vibrio rumoiensis, isolated from the H2O2-rich drain pool of a fish processing plant, was examined. When V. rumoiensiscells were inoculated into medium containing either 5 mM or no H2O2, they grew in similar manners. A spontaneous mutant strain, S-4, derived from V. rumoiensisand lacking catalase activity did not grow at all in the presence of 5 mM H2O2. These results suggest that catalase is inevitably involved in the resistance and survival of V. rumoiensis in the presence of H2O2. Catalase activity was constitutively present in V. rumoiensis cells grown in the absence of H2O2, and its occurrence was dependent on the age of the cells, a characteristic which is observed for the HP II-type catalase of Escherichia coli. The presence of the HP II-type catalase in V. rumoiensis cells was evidenced by partial sequencing of the gene encoding the HP II-type catalase from this organism. A notable difference between V. rumoiensisand E. coli is that catalase is accumulated at very high levels (∼2% of the total soluble proteins) in V. rumoiensis, in contrast to the case for E. coli. WhenV. rumoiensis cells which had been exposed to 5 mM H2O2 were centrifuged, most intracellular proteins, including catalase, were recovered in the medium. On the other hand, when V. rumoiensis cells were grown on plates containing various concentrations of H2O2, individual cells had a colony-forming ability inferior to those ofE. coli, Bacillus subtilis, and Vibrio parahaemolyticus. Thus, it is suggested that when V. rumoiensis cells are exposed to high concentrations of H2O2, most cells will immediately be broken by H2O2. In addition, the cells which have had little or no damage will start to grow in a medium where almost all H2O2 has been decomposed by the catalase released from broken cells.

Pyruvate Decarboxylase Catalyzes Decarboxylation of Branched-Chain 2-Oxo Acids but Is Not Essential for Fusel Alcohol Production by Saccharomyces cerevisiae

1998 ◽  
Vol 64 (4) ◽  
pp. 1303-1307 ◽  
Author(s):  
Eelko G. ter Schure ◽  
Marcel T. Flikweert ◽  
Johannes P. van Dijken ◽  
Jack T. Pronk ◽  
C. Theo Verrips
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Alcohol Dehydrogenase ◽  
Pyruvate Decarboxylase ◽  
Wild Type ◽  
Alcohol Production ◽  
Whole Cells ◽  
Fusel Alcohols ◽  
Cell Extracts ◽  
Fusel Alcohol ◽  
Branched Chain

ABSTRACT The fusel alcohols 3-methyl-1-butanol, 2-methyl-1-butanol, and 2-methyl-propanol are important flavor compounds in yeast-derived food products and beverages. The formation of these compounds from branched-chain amino acids is generally assumed to occur via the Ehrlich pathway, which involves the concerted action of a branched-chain transaminase, a decarboxylase, and an alcohol dehydrogenase. Partially purified preparations of pyruvate decarboxylase (EC 4.1.1.1 ) have been reported to catalyze the decarboxylation of the branched-chain 2-oxo acids formed upon transamination of leucine, isoleucine, and valine. Indeed, in a coupled enzymatic assay with horse liver alcohol dehydrogenase, cell extracts of a wild-type Saccharomyces cerevisiae strain exhibited significant decarboxylation rates with these branched-chain 2-oxo acids. Decarboxylation of branched-chain 2-oxo acids was not detectable in cell extracts of an isogenic strain in which all threePDC genes had been disrupted. Experiments with cell extracts from S. cerevisiae mutants expressing a singlePDC gene demonstrated that both PDC1- andPDC5-encoded isoenzymes can decarboxylate branched-chain 2-oxo acids. To investigate whether pyruvate decarboxylase is essential for fusel alcohol production by whole cells, wild-type S. cerevisiae and an isogenic pyruvate decarboxylase-negative strain were grown on ethanol with a mixture of leucine, isoleucine, and valine as the nitrogen source. Surprisingly, the three corresponding fusel alcohols were produced in both strains. This result proves that decarboxylation of branched-chain 2-oxo acids via pyruvate decarboxylase is not an essential step in fusel alcohol production.

scholarly journals Evolution of resistance in vitro reveals mechanisms of artemisinin activity inToxoplasma gondii

2019 ◽  
Vol 116 (52) ◽  
pp. 26881-26891 ◽  
Author(s):  
Alex Rosenberg ◽  
Madeline R. Luth ◽  
Elizabeth A. Winzeler ◽  
Michael Behnke ◽  
L. David Sibley
Keyword(s):  
Point Mutations ◽  
Artemisinin Resistance ◽  
Wild Type ◽  
Resistant Lines ◽  
Genes Encoding ◽  
Evolution Of Resistance ◽  
Moderate Sensitivity ◽  
High Concentrations ◽  
Related Parasite

Artemisinins are effective against a variety of parasites and provide the first line of treatment for malaria. Laboratory studies have identified several mechanisms for artemisinin resistance inPlasmodium falciparum, including mutations in Kelch13 that are associated with delayed clearance in some clinical isolates, although other mechanisms are likely involved. To explore other potential mechanisms of resistance in parasites, we took advantage of the genetic tractability ofToxoplasma gondii, a related parasite that shows moderate sensitivity to artemisinin. Resistant populations ofT. gondiiwere selected by culture in increasing concentrations and whole-genome sequencing identified several nonconservative point mutations that emerged in the population and were fixed over time. Genome editing using CRISPR/Cas9 was used to introduce point mutations conferring amino acid changes in a serine protease homologous to DegP and a serine/threonine protein kinase of unknown function. Single and double mutations conferred a competitive advantage over wild-type parasites in the presence of drug, despite not changing EC50values. Additionally, the evolved resistant lines showed dramatic amplification of the mitochondria genome, including genes encoding cytochromeband cytochromecoxidase I. Prior studies in yeast and mammalian tumor cells implicate the mitochondrion as a target of artemisinins, and treatment of wild-type parasites with high concentrations of drug decreased mitochondrial membrane potential, a phenotype that was stably altered in the resistant parasites. These findings extend the repertoire of mutations associated with artemisinin resistance and suggest that the mitochondrion may be an important target of inhibition of resistance inT. gondii.

Sign in / Sign up

Export Citation Format

Share Document