S-thiolation of tyrosine hydroxylase by reactive nitrogen species in the presence of cysteine or glutathione.
Tyrosine hydroxylase (TH) is the initial and rate-limiting enzyme in the biosynthesis of the neurotransmitter dopamine. Peroxynitrite (ONOO-) and nitrogen dioxide (NO2) inhibit TH catalytic function and cause nitration of protein tyrosine residues. Exposure of TH to either ONOO- or NO2 in the presence of cysteine (or glutathione) prevents tyrosine nitration and results in S-thiolation instead. TH catalytic activity is suppressed by S-thiolation. Dithiothreitol prevents and reverses the modification of TH by S-thiolation, and returns enzyme activity to control levels. S-Nitrosothiols, which are known to S-thiolate proteins, can be formed in the reaction of cysteine or glutathione with reactive nitrogen species. Therefore, S-nitrosoglutathione (GSNO) was tested for its ability to modify TH. Fresh solutions of GSNO did not modify TH, whereas decomposed GSNO resulted in extensive S-thiolation of the protein. Dimedone, a sulfenic acid trap, prevents S-thiolation of TH when included with GSNO during its decomposition. Taken together, these results show that TH is S-thiolated by ONOO- or NO2 in the presence of cysteine. S-Thiolation occurs at the expense of tyrosine nitration. Glutathione disulfide S-oxide, which forms spontaneously in the decomposition of GSNO and which is found in tissue undergoing oxidative stress, may be the species that S-thiolates TH.
Sadidi
Mahdieh
M
Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, Detroit, MI 48201, USA.
Geddes
Timothy J
TJ
Kuhn
Donald M
DM
D019921:Biotinylation; D003545:Cysteine / Q000737:chemistry / Q000494:pharmacology*; D003959:Diamines / Q000494:pharmacology; D009566:Nitrates / Q000378:metabolism; D009569:Nitric Oxide / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects; D026361:Reactive Nitrogen Species / Q000378:metabolism*; D026422:S-Nitrosoglutathione / Q000494:pharmacology*; D013438:Sulfhydryl Compounds / Q000378:metabolism*; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism*
D003959:Diamines; D009566:Nitrates; D026361:Reactive Nitrogen Species; D013438:Sulfhydryl Compounds; D009569:Nitric Oxide; D026422:S-Nitrosoglutathione; D014446:Tyrosine 3-Monooxygenase; D003545:Cysteine