TY - JOUR
T1 - Are rod outer segment ATP-ase and ATP-synthase activity expression of the same protein?
AU - Calzia, Daniela
AU - Candiani, Simona
AU - Garbarino, Greta
AU - Caicci, Federico
AU - Ravera, Silvia
AU - Bruschi, Maurizio
AU - Manni, Lucia
AU - Morelli, Alessandro
AU - Traverso, Carlo Enrico
AU - Candiano, Giovanni
AU - Tacchetti, Carlo
AU - Panfoli, Isabella
PY - 2013/7
Y1 - 2013/7
N2 - Vertebrate retinal rod outer segments (OS) consist of a stack of disks surrounded by the plasma membrane, where phototransduction takes place. Energetic metabolism in rod OS remains obscure. Literature described a so-called Mg2+-dependent ATPase activity, while our previous results demonstrated the presence of oxidative phosphorylation (OXPHOS) in OS, sustained by an ATP synthetic activity. Here we propose that the OS ATPase and ATP synthase are the expression of the same protein, i.e., of F1F o-ATP synthase. Imaging on bovine retinal sections showed that some OXPHOS proteins are expressed in the OS. Biochemical data on bovine purified rod OS, characterized for purity, show an ATP synthase activity, inhibited by classical F1Fo-ATP synthase inhibitors. Moreover, OS possess a pH-dependent ATP hydrolysis, inhibited by pH values below 7, suggestive of the functioning of the inhibitor of F1 (IF1) protein. WB confirmed the presence of IF1 in OS, substantiating the expression of F1F o ATP synthase in OS. Data suggest that the OS F1Fo ATP synthase is able to hydrolyze or synthesize ATP, depending on in vitro or in vivo conditions and that the role of IF1 would be pivotal in the prevention of the reversal of ATP synthase in OS, for example during hypoxia, granting photoreceptor survival.
AB - Vertebrate retinal rod outer segments (OS) consist of a stack of disks surrounded by the plasma membrane, where phototransduction takes place. Energetic metabolism in rod OS remains obscure. Literature described a so-called Mg2+-dependent ATPase activity, while our previous results demonstrated the presence of oxidative phosphorylation (OXPHOS) in OS, sustained by an ATP synthetic activity. Here we propose that the OS ATPase and ATP synthase are the expression of the same protein, i.e., of F1F o-ATP synthase. Imaging on bovine retinal sections showed that some OXPHOS proteins are expressed in the OS. Biochemical data on bovine purified rod OS, characterized for purity, show an ATP synthase activity, inhibited by classical F1Fo-ATP synthase inhibitors. Moreover, OS possess a pH-dependent ATP hydrolysis, inhibited by pH values below 7, suggestive of the functioning of the inhibitor of F1 (IF1) protein. WB confirmed the presence of IF1 in OS, substantiating the expression of F1F o ATP synthase in OS. Data suggest that the OS F1Fo ATP synthase is able to hydrolyze or synthesize ATP, depending on in vitro or in vivo conditions and that the role of IF1 would be pivotal in the prevention of the reversal of ATP synthase in OS, for example during hypoxia, granting photoreceptor survival.
KW - ATPase
KW - FF-ATP synthase
KW - IF1
KW - Rod outer segments
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U2 - 10.1007/s10571-013-9926-7
DO - 10.1007/s10571-013-9926-7
M3 - Article
C2 - 23568658
AN - SCOPUS:84878677250
VL - 33
SP - 637
EP - 649
JO - Cellular and Molecular Neurobiology
JF - Cellular and Molecular Neurobiology
SN - 0272-4340
IS - 5
ER -