Poburko 2011 J Biol Chem
Poburko Damon, Santo-Domingo Jaime, Demaurex Nicolas (2011) Dynamic regulation of the mitochondrial proton gradient during cytosolic calcium elevations. J Biol Chem 286:11672-84. |
Β» Open Access
Poburko Damon, Santo-Domingo Jaime, Demaurex Nicolas (2011) J Biol Chem
Abstract: Mitochondria extrude protons across their inner membrane to generate the mitochondrial membrane potential (ΞΞ¨(m)) and pH gradient (ΞpH(m)) that both power ATP synthesis. Mitochondrial uptake and efflux of many ions and metabolites are driven exclusively by ΞpH(m), whose in situ regulation is poorly characterized. Here, we report the first dynamic measurements of ΞpH(m) in living cells, using a mitochondrially targeted, pH-sensitive YFP (SypHer) combined with a cytosolic pH indicator (5-(and 6)-carboxy-SNARF-1). The resting matrix pH (βΌ7.6) and ΞpH(m) (βΌ0.45) of HeLa cells at 37 Β°C were lower than previously reported. Unexpectedly, mitochondrial pH and ΞpH(m) decreased during cytosolic Ca(2+) elevations. The drop in matrix pH was due to cytosolic acid generated by plasma membrane Ca(2+)-ATPases and transmitted to mitochondria by P(i)/H(+) symport and K(+)/H(+) exchange, whereas the decrease in ΞpH(m) reflected the low H(+)-buffering power of mitochondria (βΌ5 mm, pH 7.8) compared with the cytosol (βΌ20 mm, pH 7.4). Upon agonist washout and restoration of cytosolic Ca(2+) and pH, mitochondria alkalinized and ΞpH(m) increased. In permeabilized cells, a decrease in bath pH from 7.4 to 7.2 rapidly decreased mitochondrial pH, whereas the addition of 10 ΞΌm Ca(2+) caused a delayed and smaller alkalinization. These findings indicate that the mitochondrial matrix pH and ΞpH(m) are regulated by opposing Ca(2+)-dependent processes of stimulated mitochondrial respiration and cytosolic acidification.
β’ Bioblast editor: Gnaiger E
Labels: MiParea: Respiration
Tissue;cell: HeLa Preparation: Permeabilized cells, Intact cells
Regulation: Calcium, pH Coupling state: LEAK, ROUTINE
BEC 2020.2