Disease relevance of npr

• Using the E. coli phage T7 expression system the npr gene has now been overexpressed in an E. coli genetic background [1].
• Evidence for regulation of the NADH peroxidase gene (npr) from Enterococcus faecalis by OxyR [2].
• A 34 kDa protein has been identified in crude extracts of E. faecalis that cross-reacts with polyclonal antisera to purified OxyR from E. coli and a protein(s) present in these extracts retards npr DNA fragments in gel shift assays [2].
• More recently, however, functional Cys-SOH residues have been identified in the native oxidized forms of the FAD-containing NADH peroxidase and NADH oxidase from Streptococcus faecalis; these two proteins constitute a new class within the flavoprotein disulfide reductase family [3].

High impact information on npr

• However, chemical and spectroscopic evidence demonstrate that the non-flavin redox center in NADH peroxidase is an unusual stabilized cysteine-sulfenic acid (Cys-SOH) derivative, and not a cystine disulfide as found in the disulfide reductases [4].
• Using the T7 RNA polymerase expression system, a modified plasmid vector has been developed which gives reliable, high level expression in Escherichia coli of the gene encoding streptococcal NADH peroxidase [5].
• Active-site structural comparison of streptococcal NADH peroxidase and NADH oxidase. Reconstitution with artificial flavins [6].
• Incubation of the streptococcal NADH peroxidase with 5-thio-2-nitrobenzoate under anaerobic denaturing conditions leads to the rapid incorporation of 1 eq/FAD of the aromatic thiol [7].
• NADH peroxidase from Streptococcus faecalis 10C1 has been crystallized from ammonium sulfate solutions using the hanging drop vapor diffusion method [8].

Chemical compound and disease context of npr

• The flavin-containing NADH peroxidase of Streptococcus faecalis 10C1, which catalyzes the reaction: NADH + H+ + H2O2----NAD+ + 2H2O, has been purified to homogeneity in our laboratory for analyses of both its structure and redox behavior [9].
• The active site region of CoADR has only a single cysteine residue that is similar to that in the conserved SFXXC active site motif of NADH oxidase and NADH peroxidase from Enterococcus faecalis [10].
• Quinone reductase reaction catalyzed by Streptococcus faecalis NADH peroxidase [11].
• NADH peroxidase from Enterococcus faecalis is a tetrameric flavoenzyme of 201,400 Da which employs Cys 42 as a redox-active center cycling between sulfhydryl (Cys-SH) and sulfenic acid (Cys-SOH) states along the catalytic pathway [12].
• NADH peroxidase is a flavoprotein isolated from Streptococcus faecalis which catalyzes the pyridine nucleotide-dependent reduction of hydrogen peroxide to water [13].

Biological context of npr

• The NPXase gene (npr) comprises 1341 base-pairs and is preceded by a typical ribosome binding site [1].
• Integration into the chromosome via homologous recombination was monitored using the npr gene of E. faecalis JH2-2 as a target [14].
• Integration of this construction into the JH2-2 npr gene was selected by shift temperature, from 30 degrees C to 42 degrees C. 85% of the analysed clones showed integration into the npr gene, demonstrating the practicality of this thermosensitive replicon as a genetic integrative tool for E. faecalis [14].
• DNA fragments encoding streptococcal NADH peroxidase (NPXase) have been amplified, cloned and sequenced from the genome of Streptococcus (Enterococcus) faecalis 10C1 (ATCC 11700) [1].

Associations of npr with chemical compounds

• The non-flavin redox center of the streptococcal NADH peroxidase. I. Thiol reactivity and redox behavior in the presence of urea [15].
• The residual quinone reductase activity of NADH peroxidase which has undergone oxidative inactivation of the active site Cys42 indicates that this residue is not involved in the reduction of the quinones [11].
• The role of the active site cysteine 42 in NADH peroxidase has been elucidated using biochemical and crystallographic techniques [12].
• One-electron reduction of benzoquinone accounts for about 50% of the total electron transfer catalyzed by NADH peroxidase at pH 7, with the remainder of the reduction being catalyzed by a two-electron (hydride) transfer [11].
• While the function of participating pterin and the roles of Nox, Npx, CynD, and CA in the CNO-catalyzed scavenging of CN remain to be determined, this is the first report describing the collective involvement of these four enzymes in the metabolic detoxification and utilization of CN as a bacterial nitrogenous growth substrate [16].

Analytical, diagnostic and therapeutic context of npr

• A 513 bp PCR amplification product from an internal region of this npr gene was cloned into pUCB3522Ts [14].
• Crystallization and preliminary x-ray diffraction study of the flavoprotein NADH peroxidase from Streptococcus faecalis 10C1 [8].
• Molecular cloning and analysis of the gene encoding the NADH oxidase from Streptococcus faecalis 10C1. Comparison with NADH peroxidase and the flavoprotein disulfide reductases [17].
• Substrate reduction of the streptococcal flavoprotein NADH peroxidase, followed by anaerobic denaturation and titration with 5,5'-dithiobis(2-nitrobenzoate), yields a stoichiometry of one protein thiol per mole of FAD [18].

References