S-nitrosylation of dimethylarginine dimethylaminohydrolase regulates enzyme activity: further interactions between nitric oxide synthase and dimethylarginine dimethylaminohydrolase.
The enzyme dimethylarginine dimethylaminohydrolase (DDAH) hydrolyses asymmetrically methylated arginine residues that are endogenously produced inhibitors of nitric oxide synthases (NOS). We and others have proposed that DDAH activity is a key determinant of intracellular methylarginine concentrations and that factors that regulate the activity of DDAH may modulate nitric oxide (NO) production in vivo. We recently solved the crystal structure of a bacterial DDAH and identified a Cys-His-Glu catalytic triad [Murray-Rust, J., Leiper, J. M., McAlister, M., Phelan, J., Tilley, S., Santa Maria, J., Vallance, P. & McDonald, N. (2001) Nat. Struct. Biol. 8, 679-683]. The presence of a reactive cysteine residue (Cys-249) in the active site of DDAH raised the possibility that DDAH activity might be directly regulated by S-nitrosylation of this residue by NO. In the present study, we demonstrate that recombinant DDAH is reversibly inhibited after incubation with NO donors in vitro. Similarly mammalian DDAH in cytosolic extracts is also reversibly inhibited by NO donors. In cultured endothelial cells, heterologously expressed human DDAH II was S-nitrosylated after cytokine induced expression of the inducible NOS isoforms. The implication of these findings is that under certain conditions when NO generation increases, S-nitrosylation diminishes DDAH activity and this would be expected to lead to accumulation of asymmetric dimethylarginine and inhibition of NOS. This observation may help explain why expression of iNOS often leads to inhibition of activity of constitutively expressed NOS isozymes. We also identify Cys-His-Glu as a nitrosylation motif that is conserved in a family of arginine handling enzymes.
Leiper
James
J
Centre for Clinical Pharmacology and Therapeutics, British Heart Foundation Laboratories, University College London, 5 University Street, London WC1N 6JJ, United Kingdom. james.leiper@ucl.ac.uk
Murray-Rust
Judith
J
McDonald
Neil
N
Vallance
Patrick
P
D000581:Amidohydrolases / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D020134:Catalytic Domain; D002460:Cell Line; D003545:Cysteine / Q000737:chemistry; D004229:Dithiothreitol / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D051379:Mice; D008958:Models, Molecular; D009569:Nitric Oxide / Q000378:metabolism; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II; D011550:Pseudomonas aeruginosa / Q000201:enzymology / Q000235:genetics
D004791:Enzyme Inhibitors; D020030:Nitric Oxide Donors; D009569:Nitric Oxide; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D000581:Amidohydrolases; C059999:dimethylargininase; D003545:Cysteine; D004229:Dithiothreitol