The mitochondrial ADP/ATP carrier: structural, physiological and pathological aspects

Area of Science:

• Biochemistry
• Molecular Biology
• Cellular Physiology

Background:

• The mitochondrial ADP/ATP carrier is crucial for oxidative phosphorylation, exchanging cytosolic ADP for matrix ATP across the inner mitochondrial membrane.
• Specific inhibitors, atractyloside (ATR)/carboxyatractyloside (CATR) and bongkrekic acid (BA)/isobongkrekic acid (isoBA), bind to distinct carrier conformations (CATR- and BA-conformations).

Purpose of the Study:

• To investigate the reversible conformational transitions of the ADP/ATP carrier using fluorometric techniques.
• To elucidate the molecular mechanism of ADP/ATP transport by combining fluorescence and mutagenesis approaches.
• To develop a method for quantifying the ADP/ATP carrier in muscular biopsies for diagnosing myopathies.

Main Methods:

• Fluorometric techniques utilizing intrinsic fluorescence of yeast carrier tryptophanyl residues.
• Site-directed mutagenesis of the ADP/ATP carrier protein.
• Development of a quantitative assay for carrier protein in muscular biopsies.

Main Results:

• Demonstrated reversible conformational transitions of the ADP/ATP carrier triggered by transportable nucleotides.
• Provided insights into the molecular mechanism of ADP/ATP transport through combined fluorescence and mutagenesis studies.
• Established a method for quantifying the carrier protein in muscle tissue.

Conclusions:

• The study elucidates the conformational dynamics of the mitochondrial ADP/ATP carrier, crucial for its transport function.
• The findings contribute to understanding the molecular basis of ADP/ATP transport and associated myopathies.
• A novel method for carrier quantification in biopsies offers a diagnostic tool for muscle-related disorders.