Function of microtubules in intercellular transport of plant virus RNA

Area of Science:

• Plant virology
• Molecular plant-pathology
• Cell biology

Background:

• Cell-to-cell movement of viruses like tobacco mosaic virus (TMV) is essential for systemic infection in plants.
• Virus-encoded movement proteins (MPs) facilitate this intercellular transport process.
• The precise mechanism by which MPs interact with plant cellular machinery remains incompletely understood.

Purpose of the Study:

• To investigate the molecular mechanism of TMV movement protein (MP) involvement in viral RNA transport.
• To elucidate the role of plant microtubules in the cell-to-cell progression of TMV infection.
• To identify specific regions and interactions of MP critical for its function.

Main Methods:

• Sequence analysis of conserved motifs in tobamovirus MPs.
• Site-directed mutagenesis to create temperature-sensitive MP variants.
• Assessing microtubule association and viral RNA (vRNA) intercellular transport in planta.
• Investigating the interaction of MP with microtubule-nucleation sites.

Main Results:

• A conserved sequence motif in tobamovirus MPs shows similarity to tubulin regions involved in microtubule lateral contacts.
• Point mutations in this motif resulted in temperature-sensitive MP association with microtubules and vRNA transport.
• These findings indicate that MP-interacting microtubules are functionally important for vRNA transport to plasmodesmata.
• MP was shown to interact with microtubule-nucleation sites.

Conclusions:

• The plant virus movement protein (MP) interacts with microtubules, playing a key role in viral RNA intercellular transport.
• MP may utilize tubulin assembly surfaces to facilitate vRNA movement.
• Microtubule polymerization dynamics appear to drive the process of viral RNA transport during infection.