RT info:eu-repo/semantics/article
T1 Dynamic Regulation of the Mitochondrial Proton Gradient during Cytosolic Calcium Elevations
A1 Poburko, Damon
A1 Santo-Domingo, Jaime
A1 Demaurex, Nicolas
K1 calcium, mitochondria, bioenergetics, pH
AB Mitochondria extrude protons across their inner membrane to generate the mitochondrial membrane potential (ΔΨ(m)) and pH gradient (ΔpH(m)) that both power ATP synthesis. Mitochondrial uptake and efflux of many ions and metabolites are driven exclusively by ΔpH(m), whose in situ regulation is poorly characterized. Here, we report the first dynamic measurements of ΔpH(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 (∼7.6) and ΔpH(m) (∼0.45) of HeLa cells at 37 °C were lower than previously reported. Unexpectedly, mitochondrial pH and ΔpH(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 ΔpH(m) reflected the low H(+)-buffering power of mitochondria (∼5 mm, pH 7.8) compared with the cytosol (∼20 mm, pH 7.4). Upon agonist washout and restoration of cytosolic Ca(2+) and pH, mitochondria alkalinized and ΔpH(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 μm Ca(2+) caused a delayed and smaller alkalinization. These findings indicate that the mitochondrial matrix pH and ΔpH(m) are regulated by opposing Ca(2+)-dependent processes of stimulated mitochondrial respiration and cytosolic acidification.
PB Elsevier
SN 0021-9258
YR 2011
FD 2011
LK https://uvadoc.uva.es/handle/10324/65921
UL https://uvadoc.uva.es/handle/10324/65921
LA eng
NO J Biol Chem., April 2011, 286, 13, 11672-84.
NO Producción Científica
DS UVaDOC
RD 26-jul-2024