Proximity Labelling-Based Proteomics Identifies Antiviral Host Factors Associated With the Potexvirus Replicase.

Area of Science:

• Plant virology
• Molecular biology
• Cell biology

Background:

• Plant viruses establish replication complexes (VRCs) by altering host cell membranes, particularly the endoplasmic reticulum (ER).
• Identifying host proteins interacting with viral components is crucial for understanding virus replication and developing antiviral strategies.

Purpose of the Study:

• To identify host proteins associated with the methyltransferase (MET) domain of the potexvirus Plantago asiatica mosaic virus (PlAMV) replicase.
• To investigate the subcellular localization and functional roles of these identified host factors in PlAMV replication.

Main Methods:

• Utilized a multi-control proximity labeling approach with TurboID to identify proteins proximal to the PlAMV MET domain at the ER.
• Performed subcellular localization prediction, virus-induced gene silencing, co-immunoprecipitation, and confocal microscopy to validate identified host factors.

Main Results:

• Identified 33 host factors proximal to the PlAMV MET domain, with 28 showing exclusive enrichment.
• Predicted MET-proximal proteins associate with chloroplasts, cytosol, and mitochondria, suggesting ER subdomains interface with multiple organelles.
• Validated antiviral roles for calcyclin-binding protein (NbCBP), remorin1.5 (NbREM1.5), and calcium-sensing receptor (NbCAS), as their silencing enhanced PlAMV accumulation.

Conclusions:

• Potexvirus VRCs interact with a diverse set of host factors from multiple organelles, not just the ER.
• The PlAMV MET domain localizes to specialized ER membrane subdomains that interface with other cellular compartments.
• These findings offer new insights into plant-virus interaction networks and potential targets for antiviral interventions.