HKUST Scientists Discover How DICER Enzyme Cuts RNA With High Precision in 2024

Scientists at HKUST used cryo-electron microscopy to see how DICER acts as molecular scissors. This discovery explains how the enzyme achieves perfect precision, which is vital for stopping gene errors.
By Newsroom | Science, Hong Kong |

Molecular Scissor's Secret Revealed

A recent flurry of reports highlights a significant advance in understanding the enzyme DICER, a crucial player in RNA silencing. Researchers from The Hong Kong University of Science and Technology (HKUST) have utilized advanced techniques, including high-resolution cryo-electron microscopy (cryo-EM), to visualize the enzyme's atomic-level interactions with RNA.

This work provides unprecedented structural snapshots of DICER's dynamic adjustments, revealing how it achieves single-nucleotide precision in processing microRNAs (miRNAs). This accuracy is fundamental, dictating the production of mature miRNAs that govern gene expression. For years, the precise mechanism behind DICER's cleavage accuracy remained elusive, despite its known critical role.

Structural Insights into Enzyme Flexibility

The discovered structural details illuminate how DICER undergoes "conformational adjustments" before cleaving RNA substrates. These adjustments guide the RNA into the correct "register" for precise cutting.

How DICER cuts microRNAs with single-nucleotide precision - 1

  • The study identified not only the previously known U-favoured 5′-end binding pocket but also a newly discovered G-favoured 5′-end binding pocket.

  • This structural flexibility is key to explaining DICER's ability to process precursor miRNAs with varied loop sizes and shapes, a characteristic that has long puzzled scientists.

Implications for Disease and Regulation

The heightened understanding of DICER's precise functioning has far-reaching implications.

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  • Gene regulation research is advanced by these findings.

  • New insights are offered into the molecular underpinnings of diseases such as cancer, immune disorders, and genetic diseases.

Previous observations have already linked mutations in DICER or reduced DICER activity to several cancers and developmental disorders, underscoring the enzyme's critical biological role.

Background: The Enigma of miRNA Processing

MicroRNAs (miRNAs) are small non-coding RNA molecules that play vital roles in regulating gene expression. Their biogenesis involves a complex pathway, with DICER acting as a key enzyme. DICER is responsible for cleaving double-stranded RNA precursors into short miRNA duplexes, which are then incorporated into the RNA-induced silencing complex (RISC). The accuracy of this cleavage step is paramount; even a single nucleotide difference can alter the resulting miRNA's function and its target specificity. This precision is what makes DICER one of biology's most "precise molecular scissors."

Separately, research has also focused on developing methods for detecting miRNAs with similar precision. The 'PRICE' assay, for instance, has been detailed for its capability in direct and robust detection of microRNAs at single-nucleotide resolution. This assay utilizes specific molecular probes to distinguish target miRNAs from their mutants, enabling sensitive detection even in complex mixtures.

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Frequently Asked Questions

Q: What did HKUST researchers discover about the DICER enzyme in 2024?
Researchers used high-resolution cryo-electron microscopy to see how DICER cuts RNA. They found that the enzyme changes its shape to make very precise cuts, ensuring that microRNAs are made correctly.
Q: Why is the discovery of the new G-favored binding pocket in DICER important?
This new pocket helps explain how DICER can process many different types of RNA. Before this, scientists did not know how the enzyme handled different loop sizes and shapes so accurately.
Q: How does this new understanding of DICER help with cancer and disease research?
DICER is responsible for controlling gene expression. When it does not work correctly, it can lead to cancer or immune disorders. Understanding its exact movement helps scientists find better ways to fix these errors.
Q: What are microRNAs and why does DICER need to cut them with single-nucleotide precision?
MicroRNAs are small molecules that control how genes work in the body. If DICER makes a cut that is off by even one single nucleotide, the microRNA may fail to work or target the wrong gene, which can cause illness.