Human adenine nucleotide translocases physically and functionally interact with respirasomes

Area of Science:

• Mitochondrial biology
• Cellular respiration
• Biochemistry

Background:

• Adenine nucleotide translocases (ANTs) are crucial for ATP/ADP exchange across the mitochondrial inner membrane, vital for oxidative phosphorylation (OXPHOS).
• ANT dysregulation is linked to various diseases, including cardiomyopathy and intellectual disability, yet their binding partners remain largely unidentified.
• Understanding ANT interactions is key to elucidating disease mechanisms and disparate phenotypic manifestations.

Purpose of the Study:

• To systematically identify the protein interactomes of two human ANT isoforms.
• To investigate the functional consequences of ANT interactions, particularly with the respiratory supercomplex (RSC).
• To elucidate the molecular basis of ANT-associated diseases.

Main Methods:

• Proteomic analysis to define the interactomes of human ANT isoforms.
• Investigating ANT association with heterologous partner proteins, including the respiratory supercomplex (RSC) and other solute carriers.
• Assessing the impact of ANT isoform absence and OXPHOS inhibition on ANT function and mitochondrial respiration in HEK293 cells.

Main Results:

• Human ANTs associate with heterologous proteins, including the respiratory supercomplex (RSC) and other solute carriers.
• The ANT-RSC association is evolutionarily conserved, despite differences in RSC composition between yeast and humans.
• Absence of the major ANT isoform had a modest impact on OXPHOS, suggesting functional redundancy; however, OXPHOS inhibition impaired ANT-dependent ADP/ATP exchange.

Conclusions:

• ANTs physically interact with and functionally cooperate with the OXPHOS machinery.
• This interaction enhances ANT transport capacity and mitochondrial respiration.
• The findings provide molecular insights into ANT function and associated diseases, highlighting the importance of ANT-RSC interactions.