TY - JOUR
T1 - WrbA from Escherichia coli and Archaeoglobus fulgidus is an NAD(P)H:quinone oxidoreductase
AU - Patridge, Eric V.
AU - Ferry, James G.
PY - 2006/5
Y1 - 2006/5
N2 - WrbA (tryptophan [W] repressor-binding protein) was discovered in Escherichia coli, where it was proposed to play a role in regulation of the tryptophan operon; however, this has been put in question, leaving the function unknown. Here we report a phylogenetic analysis of 30 sequences which indicated that WrbA is the prototype of a distinct family of flavoproteins which exists in a diversity of cell types across all three domains of life and includes documented NAD(P)H:quinone oxidoreductases (NQOs) from the Fungi and Viridiplantae kingdoms. Biochemical characterization of the prototypic WrbA protein from E. coli and WrbA from Archaeoglobus fulgidus, a hyperthermophilic species from the Archaea domain, shows that these enzymes have NQO activity, suggesting that this activity is a defining characteristic of the WrbA family that we designate a new type of NQO (type IV). For E. coli WrbA, the K mNADH was 14 ± 0.43 μM and the K mbenzoquinone was 5.8 ± 0.12 μM. For A. fulgidus WrbA, the KmNADH was 19 ± 1.7 μM and the K mbenzoquinone was 37 ± 3.6 μM. Both enzymes were found to be homodimeric by gel filtration chromatography and homotetrameric by dynamic light scattering and to contain one flavin mononucleotide molecule per monomer. The NQO activity of each enzyme is retained over a broad pH range, and apparent initial velocities indicate that maximal activities are comparable to the optimum growth temperature for the respective organisms. The results are discussed and implicate WrbA in the two-electron reduction of quinones, protecting against oxidative stress.
AB - WrbA (tryptophan [W] repressor-binding protein) was discovered in Escherichia coli, where it was proposed to play a role in regulation of the tryptophan operon; however, this has been put in question, leaving the function unknown. Here we report a phylogenetic analysis of 30 sequences which indicated that WrbA is the prototype of a distinct family of flavoproteins which exists in a diversity of cell types across all three domains of life and includes documented NAD(P)H:quinone oxidoreductases (NQOs) from the Fungi and Viridiplantae kingdoms. Biochemical characterization of the prototypic WrbA protein from E. coli and WrbA from Archaeoglobus fulgidus, a hyperthermophilic species from the Archaea domain, shows that these enzymes have NQO activity, suggesting that this activity is a defining characteristic of the WrbA family that we designate a new type of NQO (type IV). For E. coli WrbA, the K mNADH was 14 ± 0.43 μM and the K mbenzoquinone was 5.8 ± 0.12 μM. For A. fulgidus WrbA, the KmNADH was 19 ± 1.7 μM and the K mbenzoquinone was 37 ± 3.6 μM. Both enzymes were found to be homodimeric by gel filtration chromatography and homotetrameric by dynamic light scattering and to contain one flavin mononucleotide molecule per monomer. The NQO activity of each enzyme is retained over a broad pH range, and apparent initial velocities indicate that maximal activities are comparable to the optimum growth temperature for the respective organisms. The results are discussed and implicate WrbA in the two-electron reduction of quinones, protecting against oxidative stress.
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U2 - 10.1128/JB.188.10.3498-3506.2006
DO - 10.1128/JB.188.10.3498-3506.2006
M3 - Article
C2 - 16672604
AN - SCOPUS:33646590587
SN - 0021-9193
VL - 188
SP - 3498
EP - 3506
JO - Journal of bacteriology
JF - Journal of bacteriology
IS - 10
ER -