Myosin is reversibly inhibited by S-nitrosylation.
Nitric oxide (NO*) is synthesized in skeletal muscle and its production increases during contractile activity. Although myosin is the most abundant protein in muscle, it is not known whether myosin is a target of NO* or NO* derivatives. In the present study, we have shown that exercise increases protein S-nitrosylation in muscle, and, among contractile proteins, myosin is the principal target of exogenous SNOs (S-nitrosothiols) in both skinned skeletal muscle fibres and differentiated myotubes. The reaction of isolated myosin with S-nitrosoglutathione results in S-nitrosylation at multiple cysteine thiols and produces two populations of protein-bound SNOs with different stabilities. The less-stable population inhibits the physiological ATPase activity, without affecting the affinity of myosin for actin. However, myosin is neither inhibited nor S-nitrosylated by the NO* donor diethylamine NONOate, indicating a requirement for transnitrosylation between low-mass SNO and myosin cysteine thiols rather than a direct reaction of myosin with NO* or its auto-oxidation products. Interestingly, alkylation of the most reactive thiols of myosin by N-ethylmaleimide does not inhibit formation of a stable population of protein-SNOs, suggesting that these sites are located in less accessible regions of the protein than those that affect activity. The present study reveals a new link between exercise and S-nitrosylation of skeletal muscle contractile proteins that may be important under (patho)physiological conditions.
Nogueira
Leonardo
L
Instituto de Bioquímica Médica, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Cidade Universitária, Rio de Janeiro, RJ 21941-590, Brazil.
Figueiredo-Freitas
Cicero
C
Casimiro-Lopes
Gustavo
G
Magdesian
Margaret H
MH
Assreuy
Jamil
J
Sorenson
Martha M
MM
D000199:Actins / Q000378:metabolism; D000818:Animals; D017301:Ca(2+) Mg(2+)-ATPase / Q000378:metabolism; D002460:Cell Line; D008297:Male; D051379:Mice; D009119:Muscle Contraction; D018485:Muscle Fibers, Skeletal / Q000378:metabolism; D009218:Myosins / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism; D015538:Nitrosation; D055550:Protein Stability; D011817:Rabbits; D051381:Rats; D017207:Rats, Sprague-Dawley; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D046509:Tissue Culture Techniques
D000199:Actins; D009569:Nitric Oxide; D017301:Ca(2+) Mg(2+)-ATPase; D009218:Myosins; D000254:Sodium-Potassium-Exchanging ATPase