Glutathiolation of proteins by glutathione disulfide S-oxide derived from S-nitrosoglutathione - Modifications of rat brain neurogranin/RC3 and neuromodulin/GAP-43
Jf. Li et al., Glutathiolation of proteins by glutathione disulfide S-oxide derived from S-nitrosoglutathione - Modifications of rat brain neurogranin/RC3 and neuromodulin/GAP-43, J BIOL CHEM, 276(5), 2001, pp. 3098-3105
S-Nitrosoglutathione (GSNO) undergoes spontaneous degradation that generate
s several nitrogen-containing compounds and oxidized glutathione derivative
s. We identified glutathione sulfonic acid, glutathione disulfide S-oxide (
GS(O)SG), glutathione disulfide S-dioxide, and GSSG as the major decomposit
ion products of GSNO. Each of these compounds and GSNO were tested for thei
r efficacies to modify rat brain neurogranin/RC3 (Ng) and neuromodulin/GAP-
43 (Nm), Among them, GS(O)SG was found to be the most potent in causing glu
tathiolation of both proteins; four glutathiones were incorporated into the
four Cys residues of Ng, and two were incorporated into the two Cys residu
es of Nm. Ng and Nm are two in vivo substrates of protein kinase C; their p
hosphorylations by protein kinase C attenuate the binding affinities of bot
h proteins for calmodulin. When compared with their respective unmodified f
orms, the glutathiolated Ng was a poorer substrate and glutathiolated Nm a
better substrate for protein kinase C. Glutathiolation of these two protein
s caused no change in their binding affinities for calmodulin. Treatment of
[S-35]cysteine-labeled rat brain slices with xanthine/xanthine oxidase or
a combination of xanthine/xanthine oxidase with sodium nitroprusside result
ed in an increase in cellular level of GS(O)SG. These treatments, as well a
s those by other oxidants, all resulted in an increase in thiolation of pro
teins; among them, thiolation of Ng was positively identified by immunoprec
ipitation. These results show that GS(O)SG is one of the most potent glutat
hiolating agents generated upon oxidative stress.