The RAVE complex is an isoform-specific V-ATPase assembly factor in yeast

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• The regulator of ATPase of vacuoles and endosomes (RAVE) complex is involved in vacuolar H(+)-translocating ATPase (V-ATPase) assembly and activity.
• Yeast rav1 mutants show a Vma(-) growth defect, indicating V-ATPase dysfunction, particularly at high temperatures.

Purpose of the Study:

• To investigate the role of the RAVE complex in V-ATPase assembly and function.
• To identify genetic interactions and understand the isoform specificity of RAVE in V-ATPase regulation.

Main Methods:

• Synthetic genetic analysis was employed to identify mutations exacerbating the rav1 mutation's Vma(-) phenotype.
• Interaction studies and localization assays (e.g., Stv1-green fluorescent protein) were performed.
• Overexpression studies were conducted to assess the impact of STV1 on growth defects.

Main Results:

• Synthetic genetic analysis revealed class E vps mutations cause temperature-independent Vma(-) growth defects when combined with rav1.
• RAVE directly interacts with the Vph1p subunit of V-ATPase.
• STV1 overexpression suppressed growth defects and enabled RAVE-independent V-ATPase assembly in vacuoles.
• Mutations causing synthetic defects altered Stv1-green fluorescent protein localization.

Conclusions:

• RAVE is essential for the assembly of Vph1p-containing V-ATPases but not Stv1p-containing V-ATPases.
• Synthetic Vma(-) phenotypes result from combined defects in Vph1p and Stv1p V-ATPase complexes.
• RAVE is identified as the first isoform-specific V-ATPase assembly factor.