Engineering of IF₁ -susceptive bacterial F₁ -ATPase

Area of Science:

• Biochemistry and Molecular Biology
• Enzyme Inhibition
• Mitochondrial Function

Background:

• Mitochondrial ATP synthase (MF1) is selectively inhibited by IF1, a unique characteristic despite sequence homology with bacterial F1.
• Understanding the molecular basis of IF1's selectivity is crucial for developing targeted inhibitors.

Purpose of the Study:

• To engineer thermophilic Bacillus F1 (TF1) to be susceptible to IF1 inhibition.
• To elucidate the molecular mechanism underlying IF1's selective recognition of mitochondrial F1.

Main Methods:

• Construction and testing of hybrid F1 enzymes using subunits from bovine MF1 and TF1.
• Site-directed mutagenesis of TF1 based on sequence and structural analysis of MF1 and TF1.
• Analysis of IF1 susceptibility in wild-type and mutant F1 enzymes.

Main Results:

• IF1 susceptibility was conferred to TF1 primarily through the beta subunit of mitochondrial origin.
• Five non-conserved C-terminal residues of the beta subunit were identified as critical for IF1 binding.
• Mutations in alpha and gamma subunits further enhanced IF1 susceptibility, indicating an additive effect.

Conclusions:

• Specific residues in the beta subunit of mitochondrial F1 are essential for IF1 recognition and inhibition.
• The findings provide insights into the molecular mechanism of IF1 selectivity.
• This study facilitates the development of novel inhibitors targeting bacterial ATP synthase.