Rows of ATP Synthase Dimers in Native Mitochondrial Inner Membranes

Abstract

The ATP synthase is a nanometric rotary machine that uses a transmembrane electrochemical gradient to form ATP. The structures of most components of the ATP synthase are known, and their organization has been elucidated. However, the supramolecular assembly of ATP synthases in biological membranes remains unknown. Here we show with submolecular resolution the organization of ATP synthases in the yeast mitochondrial inner membranes. The atomic force microscopy images we have obtained show how these molecules form dimers with characteristic 15 nm distance between the axes of their rotors through stereospecific interactions of the membrane embedded portions of their stators. A different interaction surface is responsible for the formation of rows of dimers. Such an organization elucidates the role of the ATP synthase in mitochondrial morphology. Some dimers have a different morphology with 10 nm stalk-to-stalk distance, in line with ATP synthases that are accessible to IF 1 inhibition. Rotation torque compensation within ATP synthase dimers stabilizes the ATP synthase structure, in particular the stator-rotor interaction. Data analysis All image treatment and analysis of AFM topographs were performed using custom-written routines for the ImageJ image processing package (23,24) and IGOR PRO (Wavemetrics, Portland, OR).

Assessing Actual Contribution of IF1, Inhibitor of Mitochondrial FoF1, to ATP Homeostasis, Cell Growth, Mitochondrial Morphology, and Cell Viability

“…IF1 Does Not Affect Mitochondria Morphology-Previous studies reported that knockdown of IF1 caused stimulation of autophagy, decrease in mitochondrial volume fraction in the cell, and decrease in cristae density in mitochondria (10,11,13,14). However, none of these were observed for IF1-KD cells with certainty in our study.…”

F-ATPase of Drosophila melanogaster Forms 53-Picosiemen (53-pS) Channels Responsible for Mitochondrial Ca2+-induced Ca2+ Release

“…Ref. 19) and suggests that the sense of rotation of F-ATPase influences the mCrC of Drosophila mitochondria, possibly by modulating accessibility of Ca 2ϩ -sensitive site(s) that trigger channel opening (20).…”

Evidence of the Proximity of ATP Synthase Subunits 6 (a) in the Inner Mitochondrial Membrane and in the Supramolecular Forms of Saccharomyces cerevisiae ATP Synthase

“…Previously, the association of ATP synthases in the mitochondrial membrane was evidenced from chemical cross-linking (15,16) and in vivo cross-linking experiments (17). More recently, atomic force microscopy and electron microscopy experiments revealed the oligomeric state of the enzyme in the inner mitochondrial membrane of yeast (12,18) and the presence of dimer ribbons of ATP synthase in mammalian mitochondria (19) and Polytomella mitochondria (20). Rows of F 1 were also observed by cryo-electron tomography of Neurospora crassa mitochondria (21).…”