Oxygen-linked S-nitrosation in fish myoglobins

A cysteine-specific tertiary allosteric effect

Signe Helbo, Andrew J. Gow, Amna Jamil, Barry D. Howes, Giulietta Smulevich, Angela Fago

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

The discovery that cysteine (Cys) S-nitrosation of trout myoglobin (Mb) increases heme O2 affinity has revealed a novel allosteric effect that may promote hypoxia-induced nitric oxide (NO) delivery in the trout heart and improve myocardial efficiency. To better understand this allosteric effect, we investigated the functional effects and structural origin of S-nitrosation in selected fish Mbs differing by content and position of reactive cysteine (Cys) residues. The Mbs from the Atlantic salmon and the yellowfin tuna, containing two and one reactive Cys, respectively, were S-nitrosated in vitro by reaction with Cys-NO to generate Mb-SNO to a similar yield (∼0.50 SH/heme), suggesting reaction at a specific Cys residue. As found for trout, salmon Mb showed a low O2 affinity (P50 = 2.7 torr) that was increased by S-nitrosation (P50 = 1.7 torr), whereas in tuna Mb, O2 affinity (P50 = 0.9 torr) was independent of S-nitrosation. O2 dissociation rates (koff) of trout and salmon Mbs were not altered when Cys were in the SNO or N-ethylmaleimide (NEM) forms, suggesting that S-nitrosation should affect O2 affinity by raising the O2 association rate (kon). Taken together, these results indicate that O2-linked S-nitrosation may occur specifically at Cys107, present in salmon and trout Mb but not in tuna Mb, and that it may relieve protein constraints that limit O2 entry to the heme pocket of the unmodified Mb by a yet unknown mechanism. UV-Vis and resonance Raman spectra of the NEM-derivative of trout Mb (functionally equivalent to Mb-SNO and not photolabile) were identical to those of the unmodified Mb, indicating that S-nitrosation does not affect the extent or nature of heme-ligand stabilization of the fully ligated protein. The importance of S-nitrosation of Mb in vivo is confirmed by the observation that Mb-SNO is present in trout hearts and that its level can be significantly reduced by anoxic conditions.

Original languageEnglish
Article numbere97012
JournalPLoS One
Volume9
Issue number5
DOIs
Publication statusPublished - 30 May 2014
Externally publishedYes

Fingerprint

Nitrosation
myoglobin
Myoglobin
Fish
Cysteine
cysteine
Fishes
Oxygen
Trout
oxygen
trout
fish
heme
Tuna
Heme
Salmon
salmon
Ethylmaleimide
tuna
nitric oxide

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Medicine(all)

Cite this

Helbo, S., Gow, A. J., Jamil, A., Howes, B. D., Smulevich, G., & Fago, A. (2014). Oxygen-linked S-nitrosation in fish myoglobins: A cysteine-specific tertiary allosteric effect. PLoS One, 9(5), [e97012]. https://doi.org/10.1371/journal.pone.0097012

Oxygen-linked S-nitrosation in fish myoglobins : A cysteine-specific tertiary allosteric effect. / Helbo, Signe; Gow, Andrew J.; Jamil, Amna; Howes, Barry D.; Smulevich, Giulietta; Fago, Angela.

In: PLoS One, Vol. 9, No. 5, e97012, 30.05.2014.

Research output: Contribution to journalArticle

Helbo, S, Gow, AJ, Jamil, A, Howes, BD, Smulevich, G & Fago, A 2014, 'Oxygen-linked S-nitrosation in fish myoglobins: A cysteine-specific tertiary allosteric effect', PLoS One, vol. 9, no. 5, e97012. https://doi.org/10.1371/journal.pone.0097012
Helbo, Signe ; Gow, Andrew J. ; Jamil, Amna ; Howes, Barry D. ; Smulevich, Giulietta ; Fago, Angela. / Oxygen-linked S-nitrosation in fish myoglobins : A cysteine-specific tertiary allosteric effect. In: PLoS One. 2014 ; Vol. 9, No. 5.
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