The yeast mitochondrial adenosine triphosphatase complex. Subunit stoichiometry and physical characterization

Area of Science:

• Mitochondrial biochemistry
• Protein complex stoichiometry
• Enzyme structure-function relationships

Background:

• The oligomycin-sensitive ATPase complex (also known as ATP synthase) is crucial for cellular energy production.
• Understanding the precise subunit composition is essential for elucidating its mechanism of action and assembly.

Purpose of the Study:

• To determine the subunit stoichiometry of the yeast oligomycin-sensitive ATPase complex.
• To investigate the structural integrity of the F1-ATPase subcomplex.

Main Methods:

• Immunoprecipitation of uniformly labeled yeast submitochondrial preparations.
• Use of subunit-specific and holoenzyme antisera.
• Triton X-100 solubilization of the enzyme complex.

Main Results:

• The Triton-solubilized ATPase complex comprises 10 distinct subunit types.
• The stoichiometry of subunits, by decreasing molecular weight, is 3:3:1:2:1:2:2:1:2:3.
• The complex has an estimated molecular weight of 5.8 x 10(5) and contains at least 20 polypeptide chains.
• The stoichiometry of the three largest subunits in the soluble F1-ATPase is conserved.

Conclusions:

• Stoichiometry data align with gel filtration and sedimentation studies, validating the molecular weight estimations.
• The findings provide insights into the structural organization, functional roles, and assembly pathways of the mitochondrial ATPase complex.