scholarly journals Identification and Characterization of a New Organic Hydroperoxide Resistance (ohr) Gene with a Novel Pattern of Oxidative Stress Regulation from Xanthomonas campestrispv. phaseoli

1998 ◽  
Vol 180 (10) ◽  
pp. 2636-2643 ◽  
Author(s):  
Skorn Mongkolsuk ◽  
Wipa Praituan ◽  
Suvit Loprasert ◽  
Mayuree Fuangthong ◽  
Sangpen Chamnongpol
Keyword(s):  
Xanthomonas Campestris ◽  
Expression Patterns ◽  
The Novel ◽  
Organic Hydroperoxide ◽  
Alkyl Hydroperoxide ◽  
Growth Inhibitory ◽  
Low Concentrations ◽  
Organic Hydroperoxides ◽  
New Type ◽  
Increased Sensitivity

ABSTRACT We have isolated a new organic hydroperoxide resistance (ohr) gene from Xanthomonas campestris pv. phaseoli. This was done by complementation of anEscherichia coli alkyl hydroperoxide reductase mutant with an organic hydroperoxide-hypersensitive phenotype. ohrencodes a 14.5-kDa protein. Its amino acid sequence shows high homology with several proteins of unknown function. An ohr mutant was subsequently constructed, and it showed increased sensitivity to both growth-inhibitory and killing concentrations of organic hydroperoxides but not to either H2O2 or superoxide generators. No alterations in sensitivity to other oxidants or stresses were observed in the mutant. ohr had interesting expression patterns in response to low concentrations of oxidants. It was highly induced by organic hydroperoxides, weakly induced by H2O2, and not induced at all by a superoxide generator. The novel regulation pattern of ohrsuggests the existence of a second organic hydroperoxide-inducible system that differs from the global peroxide regulator system, OxyR. Expression of ohr in various bacteria tested conferred increased resistance totert-butyl hydroperoxide killing, but this was not so for wild-type Xanthomonas strains. The organic hydroperoxide hypersensitivity of ohr mutants could be fully complemented by expression of ohr or a combination of ahpC and ahpF and could be partially complemented by expression ahpC alone. The data suggested that Ohr was a new type of organic hydroperoxide detoxification protein.

scholarly journals Exposure to Cadmium Elevates Expression of Genes in the OxyR and OhrR Regulons and Induces Cross-Resistance to Peroxide Killing Treatment in Xanthomonas campestris

2005 ◽  
Vol 71 (4) ◽  
pp. 1843-1849 ◽  
Author(s):  
Peerakan Banjerdkij ◽  
Paiboon Vattanaviboon ◽  
Skorn Mongkolsuk
Keyword(s):  
Induced Resistance ◽  
Stress Responses ◽  
Xanthomonas Campestris ◽  
Cadmium Toxicity ◽  
Cross Resistance ◽  
Organic Hydroperoxide ◽  
Alkyl Hydroperoxide ◽  
Expression Of Genes ◽  
Low Concentrations ◽  
Peroxide Stress

ABSTRACT Cadmium is an important heavy metal pollutant. For this study, we investigated the effects of cadmium exposure on the oxidative stress responses of Xanthomonas campestris, a soil and plant pathogenic bacterium. The exposure of X. campestris to low concentrations of cadmium induces cross-protection against subsequent killing treatments with either H2O2 or the organic hydroperoxide tert-butyl hydroperoxide (tBOOH), but not against the superoxide generator menadione. The cadmium-induced resistance to peroxides is due to the metal's ability to induce increased levels of peroxide stress protective enzymes such as alkyl hydroperoxide reductase (AhpC), monofunctional catalase (KatA), and organic hydroperoxide resistance protein (Ohr). Cadmium-induced resistance to H2O2 is dependent on functional OxyR, a peroxide-sensing transcription regulator. Cadmium-induced resistance to tBOOH shows a more complex regulatory pattern. The inactivation of the two major sensor-regulators of organic hydroperoxide, OxyR and OhrR, only partially inhibited cadmium-induced protection against tBOOH, suggesting that these genes do have some role in the process. However, other, as yet unknown mechanisms are involved in inducible organic hydroperoxide protection. Furthermore, we show that the cadmium-induced peroxide stress response is mediated by the metal's ability to predominately cause an increase in intracellular concentrations of organic hydroperoxide and, in part, H2O2. Analyses of various mutants of peroxide-metabolizing enzymes suggested that this increase in organic hydroperoxide levels is, at least in part, responsible for cadmium toxicity in Xanthomonas.

scholarly journals Important Role for Methionine Sulfoxide Reductase in the Oxidative Stress Response of Xanthomonas campestris pv. phaseoli

2005 ◽  
Vol 187 (16) ◽  
pp. 5831-5836 ◽  
Author(s):  
Paiboon Vattanaviboon ◽  
Chotirote Seeanukun ◽  
Wirongrong Whangsuk ◽  
Supa Utamapongchai ◽  
Skorn Mongkolsuk
Keyword(s):  
Oxidative Stress ◽  
Xanthomonas Campestris ◽  
Physiological Function ◽  
Expression Patterns ◽  
Methionine Sulfoxide ◽  
Oxidative Stress Response ◽  
Methionine Sulfoxide Reductase ◽  
Independent Manner ◽  
Reductase Gene ◽  
Increased Sensitivity

ABSTRACT A methionine sulfoxide reductase gene (msrA) from Xanthomonas campestris pv. phaseoli has unique expression patterns and physiological function. msrA expression is growth dependent and is highly induced by exposure to oxidants and N-ethylmaleimide in an OxyR- and OhrR-independent manner. An msrA mutant showed increased sensitivity to oxidants but only during stationary phase.

scholarly journals Novel Organic Hydroperoxide-Sensing and Responding Mechanisms for OhrR, a Major Bacterial Sensor and Regulator of Organic Hydroperoxide Stress

2006 ◽  
Vol 188 (4) ◽  
pp. 1389-1395 ◽  
Author(s):  
Warunya Panmanee ◽  
Paiboon Vattanaviboon ◽  
Leslie B. Poole ◽  
Skorn Mongkolsuk
Keyword(s):  
Xanthomonas Campestris ◽  
Polyacrylamide Gel Electrophoresis ◽  
Cysteine Residue ◽  
Site Directed Mutagenesis ◽  
Mass Spectrometry Analysis ◽  
Wild Type ◽  
Sulfenic Acid ◽  
Organic Hydroperoxide ◽  
Organic Hydroperoxides

ABSTRACT Xanthomonas campestris pv. phaseoli OhrR belongs to a major family of multiple-cysteine-containing bacterial organic hydroperoxide sensors and transcription repressors. Site-directed mutagenesis and subsequent in vivo functional analyses revealed that changing any cysteine residue to serine did not alter the ability of OhrR to bind to the P1 ohrR-ohr promoter but drastically affected the organic hydroperoxide-sensing and response mechanisms of the protein. Xanthomonas OhrR requires two cysteine residues, C22 and C127, to sense and respond to organic hydroperoxides. Analysis of the free thiol groups in wild-type and mutant OhrRs under reducing and oxidizing conditions indicates that C22 is the organic hydroperoxide-sensing residue. Exposure to organic hydroperoxides led to the formation of an unstable OhrR-C22 sulfenic acid intermediate that could be trapped by 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole and detected by UV-visible spectral analysis in an oxidized C127S-C131S mutant OhrR. In wild-type OhrR, the cysteine sulfenic acid intermediate rapidly reacts with the thiol group of C127, forming a disulfide bond. The high-performance liquid chromatography-mass spectrometry analysis of tryptic fragments of alkylated, oxidized OhrR and nonreducing polyacrylamide gel electrophoresis analyses confirmed the formation of reversible intersubunit disulfide bonds between C22 and C127. Oxidation of OhrR led to cross-linking of two OhrR monomers, resulting in the inactivation of its repressor function. Evidence presented here provides insight into a new organic hydroperoxide-sensing and response mechanism for OhrRs of the multiple-cysteine family, the primary bacterial transcription regulator of the organic hydroperoxide stress response.

scholarly journals A Suppressor of the Menadione-Hypersensitive Phenotype of a Xanthomonas campestris pv. phaseoli oxyR Mutant Reveals a Novel Mechanism of Toxicity and the Protective Role of Alkyl Hydroperoxide Reductase

2003 ◽  
Vol 185 (5) ◽  
pp. 1734-1738 ◽  
Author(s):  
Paiboon Vattanaviboon ◽  
Wirongrong Whangsuk ◽  
Skorn Mongkolsuk
Keyword(s):  
Xanthomonas Campestris ◽  
Fold Increase ◽  
Organic Peroxide ◽  
Protective Role ◽  
Alkyl Hydroperoxide Reductase ◽  
Stress Protection ◽  
Alkyl Hydroperoxide ◽  
Increased Sensitivity ◽  
Scavenging Enzymes ◽  
Moderately Resistant

ABSTRACT We isolated menadione-resistant mutants of Xanthomonas campestris pv. phaseoli oxyR (oxyRXp ). The oxyRR2 Xp mutant was hyperresistant to the superoxide generators menadione and plumbagin and was moderately resistant to H2O2 and tert-butyl hydroperoxide. Analysis of enzymes involved in oxidative-stress protection in the oxyRR2 Xp mutant revealed a >10-fold increase in AhpC and AhpF levels, while the levels of superoxide dismutase (SOD), catalase, and the organic hydroperoxide resistance protein (Ohr) were not significantly altered. Inactivation of ahpC in the oxyRR2 Xp mutant resulted in increased sensitivity to menadione killing. Moreover, high levels of expression of cloned ahpC and ahpF in the oxyRXp mutant complemented the menadione hypersensitivity phenotype. High levels of other oxidant-scavenging enzymes such as catalase and SOD did not protect the cells from menadione toxicity. These data strongly suggest that the toxicity of superoxide generators could be mediated via organic peroxide production and that alkyl hydroperoxide reductase has an important novel function in the protection against the toxicity of these compounds in X. campestris.

Effect of C6-Volatiles on Bioluminescent Plant Pathogens

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 557d-557
Author(s):  
Jennifer Warr ◽  
Fenny Dane ◽  
Bob Ebel
Keyword(s):  
Biological Activity ◽  
Bacterial Growth ◽  
Xanthomonas Campestris ◽  
Plant Pathogens ◽  
Genetically Engineered ◽  
The Other ◽  
Computer Assisted ◽  
Signal Molecules ◽  
Low Concentrations

C6 volatile compounds are known to be produced by the plant upon pathogen attack or other stress-related events. The biological activity of many of these substances is poorly understood, but some might produce signal molecules important in host–pathogen interactions. In this research we explored the possibility that lipid-derived C6 volatiles have a direct effect on bacterial plant pathogens. To this purpose we used a unique tool, a bacterium genetically engineered to bioluminesce. Light-producing genes from a fish-associated bacterium were introduced into Xanthomonas campestris pv. campestris, enabling nondestructive detection of bacteria in vitro and in the plant with special computer-assisted camera equipment. The effects of different C6 volatiles (trans-2 hexanal, trans-2 hexen-1-ol and cis-3 hexenol) on growth of bioluminescent Xanthomonas campestris were investigated. Different volatile concentrations were used. Treatment with trans-2 hexanal appeared bactericidal at low concentrations (1% and 10%), while treatments with the other volatiles were not inhibitive to bacterial growth. The implications of these results with respect to practical use of trans-2 hexanal in pathogen susceptible and resistant plants will be discussed.

CAD AND CAE TECHNOLOGIES OF A NOVEL PLANE SIX-BAR SWAYING MACHINE

2008 ◽  
Vol 07 (01) ◽  
pp. 65-67
Author(s):  
CHANGPING ZOU ◽  
LI DU ◽  
XIANDE HUANG
Keyword(s):  
High Pressure ◽  
Kinetic Analysis ◽  
Rotational Speed ◽  
Preliminary Analysis ◽  
Unit Weight ◽  
The Novel ◽  
Parameterized Modeling ◽  
New Type ◽  
Working Principle ◽  
Key Dimensions

A new type of six-bar swaying machine was put forward, which is an ingenious combination of plane multi-bar mechanism and high pressure oil cylinder. Preliminary analysis shows that this machine has many advantages, such as the torque produced by its unit weight, its small size, its light deadweight, etc. Thus it can be applied to situations that need swaying mechanism with low rotational speed and great torque. Firstly, the mechanism composition and working principle of the swaying machine were introduced. Secondly, parameterized modeling of the mechanism was carried out by utilizing software ADAMS. Then kinematic analysis and kinetic analysis were completed by using ADAMS. Finally, key dimensions were adjusted according to kinetic analysis. These tasks are believed to be beneficial to the development of the novel transmission.

565 POSTER Growth-inhibitory and anti-angiogenic effects of the novel MEK inhibitor PD0325901 in preclinical models of human malignant melaoma

2006 ◽  
Vol 4 (12) ◽  
pp. 171-172
Author(s):  
L. Ciuffreda ◽  
M. Desideri ◽  
D. Trisciuoglio ◽  
L. Steelman ◽  
A. Anichini ◽  
...  
Keyword(s):  
Mek Inhibitor ◽  
The Novel ◽  
Preclinical Models ◽  
Growth Inhibitory

Analysis of the expression patterns of the novel large multigene TRIM gene family (finTRIM) in zebrafish

2017 ◽  
Vol 66 ◽  
pp. 224-230 ◽  
Author(s):  
Kai Luo ◽  
Youshen Li ◽  
Lihai Xia ◽  
Wei Hu ◽  
Weihua Gao ◽  
...  
Keyword(s):  
Gene Family ◽  
Expression Patterns ◽  
The Novel

The Application of Mechanism Theory to a Textile Machinery Innovation

1976 ◽  
Vol 190 (1) ◽  
pp. 367-378 ◽  
Author(s):  
G. R. Wray
Keyword(s):  
High Speed ◽  
Practical Experience ◽  
Mechanism Analysis ◽  
The Novel ◽  
Traditional Practice ◽  
Textile Technology ◽  
Theoretical Investigations ◽  
Analysis And Synthesis ◽  
New Type ◽  
Machinery Manufacturing

The design of mechanisms for use in practical machinery applications is often of a trial-and-error nature based on traditional practice. Much emphasis has been given to the theory of mechanisms in recent years but this has yet to find wide practical application. This paper is a case study of how a basic idea, conceived by University-based inventors and intended to improve a slow method of making a textile pile fabric, became a reality in the form of a completely new type of high-speed textile machine for making an improved textile product, all within a time scale of four years. It also shows how recent University researches are further advancing its potential from both the machinery manufacturing and textile technology aspects. Step-by-step from the early experimental stages, it illustrates how the challenges of developing the novel mechanisms required for this unconventional machine and process were met by combining practical experience of traditional machinery design with theoretical investigations based on the new techniques of mechanism analysis and synthesis.

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