Disease relevance of nahG

• Both genes, nahU and nahG of Pseudomonas sp. ND6, have been cloned and overexpressed in Escherichia coli BL21 (DE3) [1].
• Both genes, nahG and nahW, have been cloned in Escherichia coli JM109 [2].
• For Moraxella Lav. 7, naphthalene oxygenase was constitutive; salicylate hydroxylase and catechol 2,3-oxygenase were inducible [3].

High impact information on nahG

• We isolated the son1 (suppressor of nim1-1) mutant, which shows full restoration of pathogen resistance without the induction of SAR-associated genes and expresses resistance when combined with a salicylate hydroxylase (nahG) transgene [4].
• However, sid mutants are not as susceptible to these pathogens as are transgenic plants expressing the nahG gene encoding an SA hydroxylase that degrades SA to catechol [5].
• When SA accumulation was prevented in ssi1 npr1-5 plants by expressing the SA-degrading salicylate hydroxylase (nahG) gene, all of the phenotypes associated with the ssi1 mutation were suppressed [6].
• Apoenzyme of Pseudomonas cepacia salicylate hydroxylase. Preparation, fluorescence property, and nature of flavin binding [7].
• The kinetic mechanism of salicylate hydroxylase as studied by initial rate measurement, rapid reaction kinetics, and isotope effects [8].

Chemical compound and disease context of nahG

• Two genes, nahG and nahW, encoding two independent salicylate 1-hydroxylases have been identified in the naphthalene-degrading strain Pseudomonas stutzeri AN10 [2].
• One strain, Pseudomonas fluorescens 5RL, which has the complete lower pathway inactivated by transposon insertion in nahG, accumulated a metabolite from phenanthrene and anthracene degradation [9].
• In this enzymatic method for salicylate in serum, Pseudomonas salicylate hydroxylase (EC 1.14.13.1) is used [10].
• A single strain of Pseudomonas cepacia cells was differentially induced to synthesize salicylate hydroxylase, 3-hydroxybenzoate 6-hydroxylase, or 4-hydroxybenzoate 3-hydroxylase [11].
• The pH dependence of the redox behavior of salicylate hydroxylase from Pseudomonas cepacia as well as the effects of salicylate, benzoate, and chloride binding is described [12].

Biological context of nahG

• Four of these mutants (pad4-1, npr1-1, eds5-1 and a double npr1-1 eds5-1 mutant) as well as Arabidopsis lines carrying a nahG transgene exhibited enhanced susceptibility to E. orontii and reduced levels of PR gene expression [13].
• However, expression of the nahG transgene did reduce the intensity of some ssi2-1-conferred phenotypes, including PR-1 expression, and disease resistance [14].
• Tn5 insertion mutations defining a regulatory gene, nahR, of the naphthalene catabolic pathway encoded by the NAH7 plasmid were mapped within a small NAH7 region only a few hundred bases upstream of the nahG gene, the most promoter-proximal gene of the nahGHIJK operon [15].
• Furthermore, cell death is suppressed in transgenic cad1 plants expressing nahG, which encodes an SA-degrading enzyme [16].
• Sequencing, RFLP analyses and experiments utilizing a lacZ transcriptional reporter fused to the promoter regions of nahR and nahG in Pseudomonas putida Cg1 confirmed that regulation of naphthalene degradation in both P. putida Cg1 and the type strain, P. putida NCIB 9816-4, is consistent with that of NAH7 from P. putida G7 [17].

Anatomical context of nahG

• By cultivation of Escherichia coli BL21 (DE3)/pSAH8 in LB medium at 37 degrees C with isopropyl-b-D-thiogalactopyranoside as the inducer, salicylate hydroxylase was overexpressed mainly in the form of inclusion bodies [18].
• An unusual strain of Pseudomonas putida UUC-1 capable of growth at high salicylate concentration (10 gl-1) was investigated with the aim of developing an assay and a biosensor system for determining salicylate in body fluids by utilizing the salicylate hydroxylase enzyme [19].

Associations of nahG with chemical compounds

• The nahU is an isofunctional gene of the classic salicylate hydroxylase gene, nahG, and situated outside the transcriptional unit forming the naphthalene degradation lower pathway [1].
• By using a nahG transgene, we found that salicylic acid is required for the elevated resistance caused by the dnd1 mutation but that removal of salicylic acid did not completely eliminate the dwarf and loss-of-HR phenotypes of mutant dnd1 plants [20].
• Whereas nahG was induced by some phenolic substrates that could be released by plants (i.e., salicylate, methyl salicylate, and acetyl salicylate), no induction by root extracts was observed [21].
• A strain of P. putida (NAH:Tn5/G67) defective in salicylate hydroxylase (nahG) was assessed for its ability to oxidize 1,4-dichloronaphthalene [22].
• Three bacterial flavoprotein monooxygenases, p-hydroxybenzoate hydroxylase, orcinol hydroxylase, and salicylate hydroxylase, have been examined for steady-state kinetic isotope effects with (4R)-[4-2H]NAD(P)H and (4R)-[4-3H]NAD(P)H [23].

Analytical, diagnostic and therapeutic context of nahG

• Polymerase chain reaction mapping confirmed the localization of lux transposon Tn4431 300 bp downstream from the start of the nahG gene [24].
• Molecular cloning of the nahG gene encoding salicylate hydroxylase from Pseudomonas fluorescens [25].
• Affinity chromatography of Pseudomonas salicylate hydroxylase [26].
• In this study, to obtain a better understanding of the predicted role of Lys163, this residue in the active center of salicylate hydroxylase was replaced with Arg, Gly, or Glu by conventional site-directed mutagenesis [18].
• Crystallization and preliminary X-ray analysis of salicylate hydroxylase from Pseudomonas putida S-1 [27].

References