المؤلفون: Emma Lazrove, Panah Nabili, Kambiz N. Alavian, Elizabeth A. Jonas

المصدر: ResearcherID

مصطلحات موضوعية: ATP synthase, Neurodegeneration, Biophysics, PINK1, Mitochondrion, Biology, medicine.disease, Parkin, Cell biology, medicine, biology.protein, ATP–ADP translocase, Inner mitochondrial membrane, Mitochondrial DNA replication

الوصف: The progressive loss of midbrain dopaminergic neurons is the hallmark of Parkinson's disease (PD). Defects in mitochondrial electron transport and mitochondrial DNA replication predispose to the onset of PD. The protein products of several PD genes, including Parkin, Pink1 and DJ1 are known to localize to mitochondria; pathological mutations in these genes may disrupt mitochondrial function. In a previous study we found that the anti-apoptotic protein Bcl-xL enhances the efficiency of neuronal energy metabolism by increasing total cellular ATP levels while decreasing cellular oxygen use. Bcl-xL produces this effect in part through a direct interaction with the beta subunit of the F1Fo ATP synthase. The interaction causes a decrease in leak of H+ ions across the mitochondrial inner membrane, correlated with an increase in coupling of oxidative phosphorylation. We now show that the Parkinson's disease gene-encoded protein, DJ1 (PARK7), is also associated with the ATP synthase complex and has a similar regulatory effect on enzymatic activity of the synthase and on the coupling of oxidation to phosphorylation. Pathological mutations of DJ1 may disrupt mitochondrial efficiency leading to neurodegeneration of mesencephalic dopaminergic neurons. The exact site of the leak inhibited by Bcl-xL and DJ1 is now being determined, but likely resides in or adjacent to the c-subunit ring of the ATP synthase Fo. Improved mitochondrial metabolic efficiency that accompanies decreases in H+ leak may result in long lasting changes in synaptic efficacy and survival in both healthy and at-risk neurons, suggesting a role for leak regulation in future therapeutic interventions.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::33c0d8d0bc78d989bb4486faeb9485c7Test

المؤلفون: Kambiz N. Alavian, Elizabeth A. Jonas, Emma Lazrove, Panah Nabili, Hongmei Li

المصدر: Biophysical Journal. 102(3)

مصطلحات موضوعية: Leak channel activity, ATP synthase, ATP synthase gamma subunit, biology.protein, Biophysics, Inner membrane, V-ATPase, Biology, Inner mitochondrial membrane, Ion channel, ATP synthase alpha/beta subunits, Cell biology

الوصف: The F1FO ATP synthase is a multiple protein mitochondrial inner membrane complex that is responsible for the production of energy in the form of ATP for eukaryotic cells. It is known that the efficiency of ATP production by the F1FO ATP synthase is attenuated by an inner mitochondrial membrane leak of hydrogen ions. Previous work has shown that this leak is regulated and that its modulation protects neurons from cell death stimuli. Nevertheless, the exact molecular identity of the proton leak channel is unknown. Herein we describe, using electrophysiological techniques, a previously undetected non-selective ion channel in the c-subunit ring of the ATP synthase. The channel conductance is markedly decreased by adenine nucleotides and blocked by recombinant beta-subunit of the synthase. Mutation of highly conserved glycine residues within the putative channel pore increases channel conductance, attenuates responses to ATP, and compromises cell function leading to cell death. We conclude that the c-subunit ring is a highly regulated ion channel that can leak protons and other cations in order to regulate the degree of metabolic efficiency. The channel activity described in this work is different from the known characteristics of H+ tranlocator. We predict that normal c-subunit leak channel activity may become compromised during pathological events, disrupting inner membrane integrity.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::8ba23bb3c30bd3f4a753e37306518623Test

المؤلفون: Elizabeth A. Jonas, Emma Lazrove, Panah Nabili, Silvio Sacchetti, Laura Bonanni, Kambiz N. Alavian, Peter K. Smith, Hongmei Li, J. Marie Hardwick

المصدر: ResearcherID

مصطلحات موضوعية: biology, ATP synthase, Chemiosmosis, ATP hydrolysis, Biophysics, biology.protein, Bcl-xL, Oxidative phosphorylation, Patch clamp, Submitochondrial particle, Inner mitochondrial membrane, Cell biology

الوصف: The anti-apoptotic BCL-2 family protein, Bcl-xL, is highly expressed in the brain. Beside its anti-apoptotic function, Bcl-xL may contribute to activity-dependent normal functioning of neurons. In this study, using a set of gain and loss of function experiments, we find that, in hippocampal neurons, Bcl-xL enhances the efficiency of neuronal energy metabolism by increasing total cellular ATP levels, while decreasing cellular oxygen use. This effect is due to the presence of Bcl-xL in the mitochondrial inner membrane, co-localized with the (F1F0) ATP synthase, shown by immunocytochemistry and immune-electron microscopy. The interaction causes a decrease in leak of H+ ions across the mitochondrial inner membrane. The decreased leak is correlated with an increase in coupling of oxidative phosphorylation. In contrast, inhibition of Bcl-xL by pharmacological or genetic means increases a leak conductance measured by patch clamping the membrane of submitochondrial particles enriched in ATP synthase complexes (SMVs). Leaky SMVs demonstrate attenuated ability to sequester H+ during ATP hydrolysis. Additionally, Bcl-xL protein directly increases ATPase activity of the purified synthase complexes, while inhibition of endogenous Bcl-xL decreases synthase activity. The exact site of the leak is being determined by cross-linking studies and by patch clamping individual protein components of the ATP synthase reconstituted into artificial lipid vesicles. Improved mitochondrial metabolic efficiency of neurons accompanying changes in leak level may result in long lasting changes in synaptic efficacy in both physiological and pathological conditions.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::4216518b1a5d9a29ea5831f8808193adTest
https://doi.org/10.1016/j.bpj.2010.12.2700Test