Virus Protein Disrupts MicroRNA Processing by Interacting with Cell Machinery

Jim Crocker
25th May, 2024

Virus Protein Disrupts MicroRNA Processing by Interacting with Cell Machinery

Image Source: Natural Science News, 2024

Key Findings

  • Researchers at CONICET-UNLP found that citrus psorosis virus (CPsV) disrupts miRNA processing in sweet orange plants
  • Infected plants showed higher levels of unprocessed miRNA precursors and fewer mature miRNAs, indicating interference in the miRNA pathway
  • The viral 24K protein interacts with miRNA processing proteins, likely inhibiting miRNA maturation and affecting the plant's gene regulation
Sweet orange (Citrus sinensis) is a globally significant fruit crop, but virus infections can severely disrupt its cellular processes, leading to substantial economic losses. A recent study by researchers at CONICET-UNLP has shed light on how citrus psorosis virus (CPsV) affects the biogenesis of microRNAs (miRNAs) in sweet orange plants, revealing potential mechanisms behind these viral disruptions[1]. MicroRNAs are small, non-coding RNAs that regulate gene expression post-transcriptionally, playing crucial roles in various cellular processes[2]. In plants, miRNAs are processed by Dicer-like proteins and stabilized by HUA ENHANCER 1 (HEN1) before being loaded into ARGONAUTE (AGO) proteins, which mediate gene silencing[3]. This regulatory system is essential for maintaining cellular homeostasis and responding to environmental stresses, including pathogen attacks. In the study, the researchers used RT-qPCR analyses to compare miRNA levels in CPsV-infected and healthy sweet orange plants. They found that infected plants exhibited higher levels of unprocessed miRNA precursors and a corresponding reduction in mature miRNA species. This suggests that CPsV interferes with the miRNA processing pathway, potentially disrupting the plant's regulatory mechanisms. The team identified a viral suppressor of RNA silencing (VSR) protein, known as 24K, as a key player in this process. VSRs are known to counteract the host's RNA silencing defenses, which are part of the plant's immune response to viral infections[4]. The 24K protein was found to interact with miRNA precursors in vivo, making it a candidate for the observed accumulation of unprocessed miRNAs in CPsV-infected plants. Further analyses of the 24K protein revealed its RNA-binding and protein-protein interaction domains, as well as its subcellular localization patterns. Notably, 24K colocalizes with miRNA biogenesis proteins DICER-LIKE 1 (DCL1), HYPONASTIC LEAVES 1 (HYL1), and SERRATE (SE) within nuclear D-bodies. These D-bodies are crucial sites for miRNA processing[3]. The study used bimolecular fluorescence complementation and co-immunoprecipitation assays to demonstrate that 24K interacts with HYL1 and SE, suggesting that 24K may inhibit miRNA processing by directly interacting with the miRNA processing complex. This research provides valuable insights into how CPsV disrupts miRNA biogenesis in sweet orange plants. By interfering with the miRNA processing machinery, CPsV likely impairs the plant's ability to regulate gene expression, contributing to disease symptoms and economic losses. Understanding these interactions at the molecular level could inform the development of new strategies to mitigate the impact of viral infections on sweet orange crops. In summary, the study by CONICET-UNLP highlights the complex interplay between CPsV and the miRNA processing pathway in sweet orange plants. By identifying the 24K protein as a key factor in this process, the researchers have opened new avenues for exploring how viruses manipulate host regulatory mechanisms to their advantage. This work not only advances our understanding of plant-virus interactions but also underscores the importance of miRNA biogenesis in maintaining plant health[2][3][4].

BiotechGeneticsPlant Science

References

Main Study

1) Citrus psorosis virus 24K protein inhibits the processing of miRNA precursors by interacting with components of the biogenesis machinery.

Published 24th May, 2024

https://doi.org/10.1128/spectrum.03513-23

Related Studies

2) The Diverse Roles of microRNAs at the Host⁻Virus Interface.

https://doi.org/10.3390/v10080440

3) The diversity, biogenesis, and activities of endogenous silencing small RNAs in Arabidopsis.

https://doi.org/10.1146/annurev-arplant-050213-035728

4) Roles of Small RNAs in Virus-Plant Interactions.

https://doi.org/10.3390/v11090827


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