What are the proposed pathways for ATP synthase assembly in yeast?

SouravOctober 11, 2024

Answer

The assembly of ATP synthase in yeast is proposed to occur through two distinct pathways that converge at a later stage. Here are the details of these proposed pathways:

1. Two Separate Assembly Pathways

• F₁/Atp9p Pathway: This pathway is primarily responsible for the assembly of the F₁ sector of ATP synthase. It involves the incorporation of the F₁ subunits (α, β, γ, δ, and ε) along with Atp9p, which is a mitochondrial-encoded subunit that plays a role in the assembly of the Fₒ sector. The assembly of the F₁ sector is crucial for the overall functionality of ATP synthase 11.
• Atp6p/Atp8p/2 Stator Subunits/Atp10p Chaperone Pathway: This pathway focuses on the assembly of the Fₒ sector, which includes the c-ring (composed of subunits Atp6p and Atp8p) and the stator subunits. Atp10p is a chaperone that assists in the proper folding and assembly of these components. This pathway ensures that the membrane-embedded part of ATP synthase is correctly formed and integrated into the inner mitochondrial membrane 11.

2. Convergence at the Final Assembly Stage

• Final Assembly: After the initial assembly of the F₁ and Fₒ sectors through their respective pathways, the components converge at the final assembly stage. This stage involves the integration of the F₁ and Fₒ sectors to form the complete ATP synthase complex. The precise mechanisms and factors involved in this convergence are still under investigation, but it is essential for the functional assembly of the enzyme 5.

3. Role of Assembly Factors

• Assembly Factors: Specific assembly factors, such as ATP11 and ATP12, are known to play roles in the assembly of the F₁ sector. These factors help ensure that the subunits are correctly incorporated and that the overall structure of ATP synthase is stable and functional. The existence of additional assembly factors specific to the Fₒ sector is also suggested, although they have yet to be fully characterized 11.