HC-Pro inhibits HEN1 methyltransferase activity, leading to autophagic degradation of AGO1
Abstract Helper-component proteinase (HC-Pro), encoded by potyviruses, function as viral suppressors of RNA silencing (VSRs). Despite their conserved role, HC-Pros share approximately 40% similarity, implying potential differences in VSR efficiency, particularly in their ability to inhibit HEN1 meth...
Saved in:
| Main Authors: | , , , , , , , , , , , , , , , , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Nature Portfolio
2025-03-01
|
| Series: | Nature Communications |
| Online Access: | https://doi.org/10.1038/s41467-025-56320-z |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | Abstract Helper-component proteinase (HC-Pro), encoded by potyviruses, function as viral suppressors of RNA silencing (VSRs). Despite their conserved role, HC-Pros share approximately 40% similarity, implying potential differences in VSR efficiency, particularly in their ability to inhibit HEN1 methyltransferase activity. This study investigated the inhibitory potential of HC-Pros from different potyviruses in transgenic plants. P1/HC-Pro from turnip mosaic virus (P1/HC-ProTu) exhibited the most potent inhibition of HEN1, followed by P1/HC-Pro from zucchini yellow mosaic virus (P1/HC-ProZy), while P1/HC-Pro from tobacco etch virus (P1/HC-ProTe) showed the weakest inhibitory effect. These differential effectual effects corresponded to variations in unmethylated microRNAs (unMet-miRNAs) accumulation across the transgenic lines. Fluorescence resonance energy transfer (FRET) analysis indicated that HC-ProTu recruits HEN1 and ATG8a to HC-Pro bodies (H-bodies) and indirectly associates with AGO1, potentially influencing the assembly of the RNA-induced silencing complex (RISC) and leading to the accumulation of free-form miRNA duplexes. The ability of HC-ProTu to sequester HEN1 and AGO1 in H-bodies may, therefore, modulate miRNA loading. This observation aligns with the finding that P1/HC-Pro Tu plants harbored approximately 50% unMet-miRNAs and exhibited the lowest AGO1 levels, suggesting a positive correlation between HEN1 inhibition and autophagic degradation of AGO1. Interestingly, unMet-miRNAs are absent in the AGO1 of P1/HC-Pro Tu plants but reappeared in P1/HC-Pro Tu /hen1-8/heso1-1 plants, accompanied by signs of AGO1 recovery. These findings highlight the functional diversity of HC-Pro VSRs and provide new insights into their differential effects on miRNA methylation, RISC assembly, and the regulation of RNA silencing pathways. |
|---|---|
| ISSN: | 2041-1723 |