Two distinct regions in a yeast myosin-V tail domain are required for the movement of different cargoes

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• Myosin-V motor proteins are essential for intracellular transport.
• In Saccharomyces cerevisiae, Myo2p is a myosin-V critical for polarized growth and vacuole inheritance.
• The globular tail of Myo2p is implicated in cargo binding.

Purpose of the Study:

• To identify specific regions within the Myo2p globular tail domain responsible for distinct cellular functions.
• To investigate the roles of different Myo2p tail subdomains in polarized growth and vacuole inheritance.

Main Methods:

• Random mutagenesis of the Myo2p globular tail domain.
• Isolation and characterization of single point mutants affecting vacuole inheritance.
• Analysis of a specific deletion mutant (myo2-DeltaAflII) for its effects on growth and vacuole inheritance.
• Overexpression studies of Myo2p tail domains.

Main Results:

• Six point mutants were identified that impair vacuole inheritance but not polarized growth, clustering to a specific region of the tail.
• A deletion mutant (myo2-DeltaAflII) revealed a distinct region essential for polarized growth but not vacuole inheritance.
• Overexpression of the myo2-DeltaAflII globular tail disrupted vacuole movement, indicating this region is dispensable for polarized growth.

Conclusions:

• The Myo2p globular tail contains at least two distinct subdomains, one for vacuole movement and another for polarized growth.
• These findings suggest a mechanism for how myosin-Vs can transport multiple cargoes.
• The data imply that the vacuole receptor for Myo2p is different from the receptor for essential growth-related cargo.