Nitration of specific tyrosines in FoF1 ATP synthase and activity loss in aging.
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.
University of California, Davis, Department of Molecular Biosciences, 1120 Haring Hall, One Shields Ave., Davis, CA 95616, USA.
Virginia
V
Haynes
Nathaniel J
NJ
Traaseth
Sarah
S
Elfering
Yasuko
Y
Fujisawa
Cecilia
C
Giulivi
D000255:Adenosine Triphosphate / Q000378:metabolism; D000367:Age Factors; D000375:Aging / Q000378:metabolism*; D000704:Analysis of Variance; D000818:Animals; D001665:Binding Sites; D015153:Blotting, Western; D002851:Chromatography, High Pressure Liquid; D015180:Electrophoresis, Gel, Two-Dimensional; D047468:Immunoprecipitation; D008099:Liver / Q000378:metabolism*; D008297:Male; D008928:Mitochondria / Q000378:metabolism; D025261:Mitochondrial Proton-Translocating ATPases / Q000378:metabolism*; D009566:Nitrates / Q000378:metabolism*; D018384:Oxidative Stress; D051381:Rats; D017208:Rats, Wistar; D014443:Tyrosine / Q000378:metabolism*
D009566:Nitrates; D014443:Tyrosine; D000255:Adenosine Triphosphate; D025261:Mitochondrial Proton-Translocating ATPases