Molecular basis of V-ATPase inhibition by bafilomycin A1

Area of Science:

• Biochemistry
• Structural Biology
• Cell Biology

Background:

• Vacuolar-type H+-ATPase (V-ATPase) inhibition impacts tumor metastasis, autophagy, and cellular signaling.
• Bafilomycin A1 is a potent V-ATPase inhibitor and autophagy inhibitor.
• The molecular mechanism of V-ATPase-specific inhibitors remains unclear.

Purpose of the Study:

• To determine the cryo-electron microscopy (cryo-EM) structure of bovine V-ATPase bound to bafilomycin A1.
• To elucidate the molecular basis of bafilomycin A1 inhibition on V-ATPase.

Main Methods:

• Cryo-electron microscopy (cryo-EM) to determine the structure of intact bovine V-ATPase.
• Structural and sequence analyses to identify inhibitor binding sites and conserved residues.

Main Results:

• The cryo-EM structure of bafilomycin A1-bound V-ATPase was resolved at 3.6-Å.
• Six bafilomycin A1 molecules were observed bound to the V-ATPase c-ring.
• One bafilomycin A1 molecule disrupts c-ring and subunit a interactions, inhibiting proton translocation.
• Bafilomycin A1 binding residues are conserved across yeast and mammalian species.
• The 7'-hydroxyl group of bafilomycin A1 is crucial for recognition by the c subunit.

Conclusions:

• The study reveals the precise binding mode of bafilomycin A1 to V-ATPase.
• This structural information clarifies how bafilomycin A1 inhibits proton translocation.
• Conserved binding sites suggest potential for developing new V-ATPase inhibitors for therapeutic applications.