Cellular environment is important in controlling V-ATPase dissociation and its dependence on activity

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• V-ATPase activity is regulated by reversible dissociation into V(1) and V(0) domains.
• This dissociation is linked to glucose levels in yeast.
• Different isoforms of subunit a target V-ATPases to distinct cellular compartments like the vacuole and Golgi.

Purpose of the Study:

• To investigate how the subunit a isoform and cellular environment influence V-ATPase dissociation.
• To determine the role of V-ATPase catalytic activity in the dissociation process.
• To examine dissociation in specific cellular compartments using yeast mutants.

Main Methods:

• Utilized vacuolar protein sorting (vps) mutants (vps27Δ and vps21Δ) to isolate V-ATPase complexes in different compartments (PVC and PGC).
• Assessed dissociation of Vph1p (VCC) and Stv1p (SCC) containing complexes.
• Employed concanamycin and specific Vph1p mutants (R735Q, R735K) to probe the dependence on V-ATPase activity.

Main Results:

• V-ATPase dissociation is dependent on the cellular environment, occurring most readily in the vacuole and least in the prevacuolar compartment (PVC).
• Concanamycin partially inhibits dissociation, with greater effect on SCC than VCC.
• V-ATPase catalytic activity is not absolutely required for dissociation, as demonstrated by mutants R735Q and R735K.

Conclusions:

• Cellular environment plays a significant role in controlling in vivo V-ATPase dissociation.
• The dependence of V-ATPase dissociation on catalytic activity varies and is not absolute.
• V-ATPase dissociation can proceed independently of full catalytic function, suggesting complex regulatory mechanisms.