Myosin from alga Chara: unique structure revealed by electron microscopy

Area of Science:

• Plant Cell Biology
• Molecular Motor Proteins
• Biochemistry

Background:

• Cytoplasmic streaming is essential for intracellular transport in plant cells, facilitating the movement of molecules and organelles.
• Myosin motor proteins are crucial for various cellular transport processes, but their specific roles in plant cytoplasmic streaming are not fully elucidated.

Purpose of the Study:

• To purify and characterize the myosin-like protein responsible for cytoplasmic streaming in the freshwater alga Chara corallina.
• To investigate the structural and functional properties of this purified protein in relation to known myosin families.

Main Methods:

• Purification of the myosin-like protein from Chara corallina.
• Electron microscopy to determine the protein's structure.
• Cosedimentation assays with phosphatidyl serine vesicles.

Main Results:

• The purified myosin-like protein exhibits a unique structure with two heads similar to muscle myosin (myosin II) and a shorter tail with a globular end, resembling myosin V.
• The protein cosedimented with phosphatidyl serine vesicles, indicating an interaction with lipid bilayers.
• These findings suggest a role in intracellular transport, similar to non-muscle myosins.

Conclusions:

• A novel myosin-like protein involved in Chara corallina cytoplasmic streaming has been identified and characterized.
• The protein's hybrid structural features suggest evolutionary adaptations for intracellular transport in plant cells.
• This myosin likely mediates vesicle transport during cytoplasmic streaming through interactions with lipid components.