ATP-sensitive cation-channel in wheat (triticum durum Desf.): Identification and characterization of a plant mitochondrial channel by patch-clamp

Indirect evidence points to the presence of K + channels in plant mitochondria. In the present study, we report the results of the first patch clamp experiments on plant mitochondria. Single-channel recordings in 150 mM potassium gluconate have allowed the biophysical characterization of a channel with a conductance of 150 pS in the inner mitochondrial membrane of mitoplasts obtained from wheat (Triticum durum Desf.). The channel displayed sharp voltage sensitivity, permeability to potassium and cation selectivity. ATP in the mM concentration range completely abolished the activity. We discuss the possible molecular identity of the channel and its possible role in the defence mechanisms against oxidative stress in plants

A Mitochondrial calcium dynamics - checks and balances of energy physiology

Mitochondria conserve the energy released from metabolic redox reactions and supply the cell with ATP. When the rate of respiratory metabolism does not match ATP demand active regulation of mitochondrial function is essential. For plants particularly sophisticated regulation strategies can be expected, to ensure maintenance of homeostasis in the presence of frequent environmental changes. Yet, the mechanisms by which such control is achieved in vivo are poorly understood. Calcium acts as a key regulator of mitochondrial energy metabolism in mammals by modulating the activity TCA cycle dehydrogenases. Calcium flux into the matrix is controlled by the recently identified mitochondrial uniporter complex. Plants contain homologues of components of the uniporter, but their function has been unclear. To understand how mitochondrial calcium dynamics are regulated and what their impact is on energy metabolism, we have combined reverse genetics with in vivo sensing of calcium. Fluorescent protein sensors and quantitative confocal imaging allow monitoring of mitochondrial energy physiology in living Arabidopsis tissues. We have found that several homologues of components of the mitochondrial calcium uniporter complex localize to mitochondria in Arabidopsis. Mutant lines have shown severely altered mitochondrial calcium levels and abnormal organellar calcium transients, providing a novel genetic handle on the dissection of the role of calcium regulation in plant mitochondria. We will discuss the specific impact of de-regulated mitochondrial calcium on the physiological network and the function of plant mitochondria

ATP-Sensitive Cation-channel in Wheat (Triticumdurum Desf.): Identification and Characterizationof a Plant Mitochondrial Channel by Patch-clamp

Indirect evidence points to the presence of K(+) channels in plant mitochondria. In the present study, we report the results of the first patch clamp experiments on plant mitochondria. Single-channel recordings in 150 mM potassium gluconate have allowed the biophysical characterization of a channel with a conductance of 150 pS in the inner mitochondrial membrane of mitoplasts obtained from wheat (Triticum durum Desf.). The channel displayed sharp voltage sensitivity, permeability to potassium and cation selectivity. ATP in the mM concentration range completely abolished the activity. We discuss the possible molecular identity of the channel and its possible role in the defence mechanisms against oxidative stress in plants. Copyright (C) 2010 S. Karger AG, Base