TY - JOUR
T1 - Noxa1 as a moderate activator of Nox2-based NADPH oxidase
AU - Kawano, Masahito
AU - Miyamoto, Kazuhiro
AU - Kaito, Yuki
AU - Sumimoto, Hideki
AU - Tamura, Minoru
N1 - Funding Information:
This work was supported by Monbu-sho Grants for Scientific Research (19510219 and 21510227). We are grateful to Dr. Kei Miyano (Department of Biochemistry, Kyushu University Graduate School of Medical Sciences) for his valuable discussions. The authors are indebted to Kazuhiro Takeuchi, Yuki Hamashima, Koichi Yoshinari, Takayuki Sasaki, and Kazuhiro Mizuki (Department of Applied Chemistry, Graduate School of Science and Engineering, Ehime University). We are grateful to Erina Morioka, Takashi Shigematsu, Takehito Fukuda, Yuki Yoshioka, Hirofumi Inoue, and Maiko Nakajima (Department of Applied Chemistry, Faculty of Engineering, Ehime University) for their technical assistance.
PY - 2012/3/1
Y1 - 2012/3/1
N2 - Noxa1 was discovered as an activating factor for Nox1, an O2 - generating enzyme. Subsequent studies have shown that Noxa1 is colocalized with Nox2 in several cell types, including vascular cells. Nox2 activation by Noxa1 has been examined in reconstituted model cells. However, little is known about the kinetic properties of Noxa1 in Nox2 activation. In the present study, we used purified cyt.b 558 (Nox2 plus p22 phox), Rac(Q61L), and Noxo1 to examine the ability of Noxa1 to activate Nox2. In the pure reconstitution system, Noxa1 activated Nox2 with lower efficiency than p67 phox, a canonical activator of Nox2. The EC 50 value of Noxa1 was considerably higher than that of p67 phox. The V max value with Noxa1 and Noxo1 was one-third of that with p67 phox and p47 phox. The EC 50 value of Noxo1 or Rac(Q61L) was also higher when Noxa1 was used. The affinity of FAD for the oxidase and the stability of the active complex were remarkably low when Noxa1 and Noxo1 were used compared with p67 phox and p47 phox. The stability was not improved by fusion of Noxa1 with Rac(Q61L). These findings show that Noxa1 has quite different kinetic properties from p67 phox and suggest that Noxa1 may function as a moderate activator of Nox2.
AB - Noxa1 was discovered as an activating factor for Nox1, an O2 - generating enzyme. Subsequent studies have shown that Noxa1 is colocalized with Nox2 in several cell types, including vascular cells. Nox2 activation by Noxa1 has been examined in reconstituted model cells. However, little is known about the kinetic properties of Noxa1 in Nox2 activation. In the present study, we used purified cyt.b 558 (Nox2 plus p22 phox), Rac(Q61L), and Noxo1 to examine the ability of Noxa1 to activate Nox2. In the pure reconstitution system, Noxa1 activated Nox2 with lower efficiency than p67 phox, a canonical activator of Nox2. The EC 50 value of Noxa1 was considerably higher than that of p67 phox. The V max value with Noxa1 and Noxo1 was one-third of that with p67 phox and p47 phox. The EC 50 value of Noxo1 or Rac(Q61L) was also higher when Noxa1 was used. The affinity of FAD for the oxidase and the stability of the active complex were remarkably low when Noxa1 and Noxo1 were used compared with p67 phox and p47 phox. The stability was not improved by fusion of Noxa1 with Rac(Q61L). These findings show that Noxa1 has quite different kinetic properties from p67 phox and suggest that Noxa1 may function as a moderate activator of Nox2.
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U2 - 10.1016/j.abb.2011.12.025
DO - 10.1016/j.abb.2011.12.025
M3 - Article
C2 - 22244833
AN - SCOPUS:84857330827
VL - 519
SP - 1
EP - 7
JO - Archives of Biochemistry and Biophysics
JF - Archives of Biochemistry and Biophysics
SN - 0003-9861
IS - 1
ER -