Nitration of specific tyrosines in FoF1 ATP synthase and activity loss in aging

• Published in: American journal of physiology: endocrinology and metabolism Vol. 298; no. 5; pp. E978 - E987
• Main Authors: Haynes, Virginia, Traaseth, Nathaniel J, Elfering, Sarah, Fujisawa, Yasuko, Giulivi, Cecilia
• Format: Journal Article
• Language: English
• Published: United States American Physiological Society 01.05.2010
• Subjects: Adenosine Triphosphate - metabolism; Age Factors; Aging - metabolism; Analysis of Variance; Animals; Binding Sites; Blotting, Western; Chromatography, High Pressure Liquid; Electrophoresis, Gel, Two-Dimensional; Immunoprecipitation; Liver - metabolism; Male; Mitochondria - metabolism; Mitochondrial Proton-Translocating ATPases - metabolism; Nitrates - metabolism; Oxidative Stress; Rats; Rats, Wistar; Tyrosine - metabolism
• ISSN: 0193-1849; 1522-1555
• DOI: 10.1152/ajpendo.00739.2009

It has been reported that C-nitration of proteins occurs under nitrative/oxidative stress; however, its role in pathophysiological situations is not fully understood. In this study, we determined that nitration of Tyr(345) and Tyr(368) in the beta-subunit of the mitochondrial F(o)F(1)-ATPase is a major target for nitrative stress in rat liver under in vivo conditions. The chemical characteristics of these Tyr make them suitable for a facilitated nitration (solvent accessibility, consensus sequence, and pK(a)). Moreover, beta-subunit nitration increased significantly with the age of the rats (from 4 to 80 weeks old) and correlated with decreased ATP hydrolysis and synthesis rates. Although its affinity for ATP binding was unchanged, maximal ATPase activity decreased between young and old rats by a factor of two. These changes directly impacted the available ATP concentration in vivo, and it was expected that they would affect multiple cellular ATP-dependent processes. For instance, at least 50% of available [ATP] in the liver of older rats would have to be committed to sustain maximal Na(+)-K(+)-ATPase activity, whereas only 30% would be required for young rats. If this requirement was not fulfilled, the osmoregulation and Na(+)-nutrient cotransport in liver of older rats would be compromised. On the basis of our studies, we propose that targeted nitration of the beta-subunit is an early marker for nitrative stress and aging.