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This anti-CRISPR stops the protein assembly line in bacteria

Phys · · 443 words · By University; San Francisco

Researchers at UC San Francisco have identified a viral protein called AcrVA2 that inhibits the CRISPR-Cas12 system in bacteria. The protein works by jamming the ribosome during the assembly of the Cas12 protein, triggering the cell's quality control mechanisms to destroy both the emerging protein and its mRNA blueprint.

open_in_new Read the original article: https://phys.org/news/2026-05-anti-crispr-protein-line-bacteria.html

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10%
Propaganda Score
confidence: 100%
Low risk. This article shows minimal use of propaganda techniques.

fact_checkFact-Check Results

9 claims extracted and verified against multiple sources including cross-references, web search, and Wikipedia.

check_circle Corroborated 3
info Single Source 3
verified Verified By Reference 1
verified Verified 1
help Insufficient Evidence 1
verified
“Bacteria fend off invading viruses with molecular scissors that slice up viral DNA—a system called CRISPR”
VERIFIED BY REFERENCE
Multiple Wikipedia entries and web search results confirm that CRISPR is a bacterial immune system that uses molecular scissors (Cas proteins) to slice viral DNA.
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wikipedia NEUTRAL — Cas9 (CRISPR-associated protein 9, formerly Cas5, Csn1, or Csx12) is a DNA cutting enzyme that is part of the CRISPR immune system in bacteria and archaea. It has been adapted to be used as a CRISPR g…
https://en.wikipedia.org/wiki/Cas9
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wikipedia NEUTRAL — Anti-CRISPR (Anti-Clustered Regularly Interspaced Short Palindromic Repeats or Acr) is a group of proteins found in phages, that inhibit the normal activity of CRISPR-Cas, the immune system of certain…
https://en.wikipedia.org/wiki/Anti-CRISPR
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wikipedia NEUTRAL — CRISPR (; acronym for clustered regularly interspaced short palindromic repeats) is a family of DNA sequences found in the genomes of prokaryotic organisms such as bacteria and archaea. Each sequence …
https://en.wikipedia.org/wiki/CRISPR
+ 3 more evidence sources
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“scientists at UC San Francisco describe how a viral "anti-CRISPR" protein sits on the bacteria's protein assembly line—which is known as a ribosome—and jams it as a CRISPR protein named Cas12 begins to form.”
CORROBORATED
Web search results specifically describe the mechanism where AcrVA2 inhibits Cas12a biogenesis by binding to the N-terminal polypeptide during translation on the ribosome, effectively jamming the process.
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web search NEUTRAL — Cas9 (or "CRISPR-associated protein 9") is an enzyme that uses CRISPR sequences as a guide to recognize and open up specific strands of DNA that are complementary to the CRISPR sequence.
https://en.wikipedia.org/wiki/CRISPR
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web search NEUTRAL — Cas12a, a prominent member of the Cas endonuclease family, plays a critical role in recognizing and cleaving foreign DNA. Phages, in retaliation, have evolved anti-CRISPR (Acr) proteins to disable the…
https://bioengineer.org/anti-crispr-sparks-cas12-mrna-decay/
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web search NEUTRAL — AcrIIIB1 exclusively inhibits CRISPR-Cas subtype III-B immunity mediated by the RNase activity of the accessory protein Csx1.Keywords: AcrIIIB; CRISPR-Cas type III accessory RNase; Cmr; Cmr2 (Cas10); …
https://pubmed.ncbi.nlm.nih.gov/31564454/
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“This triggers the ribosome's quality control mechanism to destroy the emerging protein, along with its mRNA blueprint.”
CORROBORATED
Multiple sources confirm that the binding of the anti-CRISPR protein triggers the degradation of the emerging protein and the associated mRNA blueprint via a translation-dependent mechanism.
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wikipedia NEUTRAL — CRISPR (; acronym for clustered regularly interspaced short palindromic repeats) is a family of DNA sequences found in the genomes of prokaryotic organisms such as bacteria and archaea. Each sequence …
https://en.wikipedia.org/wiki/CRISPR
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wikipedia NEUTRAL — CRISPR RNA or crRNA is a RNA transcript from the CRISPR locus. CRISPR-Cas (clustered, regularly interspaced short palindromic repeats - CRISPR associated systems) is an adaptive immune system found in…
https://en.wikipedia.org/wiki/CRISPR_RNA
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wikipedia NEUTRAL — Cas12a (CRISPR-associated protein 12a, previously known as Cpf1) is an RNA-guided endonuclease-exonuclease that forms an essential component of the CRISPR systems found in some bacteria and archaea. I…
https://en.wikipedia.org/wiki/Cas12a
+ 3 more evidence sources
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“The viral protein, called AcrVA2, is the only known anti-CRISPR that sabotages CRISPR this way.”
SINGLE SOURCE
While the mechanism of AcrVA2 is described in several search results, the specific claim that it is the 'only known' anti-CRISPR to work this way is only found in the context of the specific study/article and not independently verified as a unique global fact across multiple distinct scientific reviews.
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web search NEUTRAL — By interfering with mRNA stability during translation, anti-CRISPR proteins like AcrVA2 exemplify a refined method of gene regulation, which may be harnessed biotechnologically to modulate gene expres…
https://bioengineer.org/anti-crispr-sparks-cas12-mrna-decay/
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web search NEUTRAL — 3 Anti-CRISPR proteins. Bacteria use the most dependable immune system, CRISPR-Cas9, to defend themselves against phage attacks. Prior to the discovery of the Acr protein, the only option for phages t…
https://www.frontiersin.org/journals/plant-science/articles/…
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web search NEUTRAL — anti-CRISPR proteins: an advanced genome editor to amend the CRISPR gene editing. Front. Plant Sci.3 Anti-CRISPR proteins Bacteria use the most dependable immune system, CRISPR-Cas9, to defend themsel…
https://www.academia.edu/116985988/A_comprehensive_appraisal…
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“Joseph Bondy-Denomy, Ph.D., professor of Microbiology and Immunology at UCSF and senior author of the paper.”
VERIFIED
Official UCSF lab pages and academic profiles confirm Joseph Bondy-Denomy is a Professor in the Department of Microbiology & Immunology at UCSF.
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web search NEUTRAL — Contact Us. Joe Bondy-Denomy, Ph.D. Professor Department of Microbiology & Immunology. email: joseph.bondy-denomy@ucsf.edu.
https://bondydenomylab.com/
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web search NEUTRAL — Joseph Bondy-Denomy. University of California, San Francisco (UCSF) - Department of Microbiology and Immunology. Third Avenue and Parnassus.
https://papers.ssrn.com/sol3/cf_dev/AbsByAuth.cfm?per_id=345…
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web search NEUTRAL — "This isn't what we expected to see at all," said Joseph Bondy-Denomy, Ph.D., associate professor of microbiology and immunology at UC San Francisco and senior author of the study, which appears Feb.
https://phys.org/news/2025-02-jumbo-phages-bacteria-antibiot…
info
“The scientists, led by Nicole Marino, Ph.D., tested each step along the way—from DNA to mRNA to protein—to determine exactly when Cas12 went missing.”
SINGLE SOURCE
The evidence confirms the general biological process (DNA to mRNA to protein), but there is no independent corroboration in the provided evidence that Nicole Marino specifically led the team or conducted these specific tests in this manner outside of the primary report.
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web search NEUTRAL — Explore the steps of DNA replication, the enzymes involved, and the difference between the leading and lagging strand!
https://www.youtube.com/watch?v=Qqe4thU-os8
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web search NEUTRAL — Messenger RNA (abbreviated mRNA) is a type of single-stranded RNA involved in protein synthesis.
https://www.genome.gov/genetics-glossary/Messenger-RNA-mRNA
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web search NEUTRAL — The process that converts DNA to mRNA to protein is the foundation for how the cell functions. Programmed to self-destruct. As the intermediary messenger, mRNA is an important safety mechanism in the …
https://theconversation.com/what-is-mrna-the-messenger-molec…
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“AcrVA2 neither blocked the Cas12 gene, which would have prevented the Cas12 mRNA from being made, nor destroyed the mRNA in test tubes.”
CORROBORATED
Scientific results provided in the web search explicitly state that AcrVA2 does not inhibit DNA cleavage in vitro and specifically targets the translation process rather than blocking the gene or destroying mRNA independently of translation.
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web search NEUTRAL — 62 63 AcrVA2 specifically downregulates mRNA and protein of divergent Cas12 orthologs 64 AcrVA2 binds MbCas12a but does not inhibit DNA cleavage in vitro (Extended Data Fig. 1), 65 consistent with its…
https://bondydenomylab.com/static/pdf/publications/marino_20…
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web search NEUTRAL — Here, we report that an anti-CRISPR (AcrVA2) unexpectedly inhibits Cas12a biogenesis by triggering translation-dependent destruction of its mRNA. AcrVA2 specifically clears the mRNA of Cas12a by recog…
http://www.ndl.gov.in/re_document/biorxiv/biorxiv/_content_1…
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web search NEUTRAL — Cas12a, a prominent member of the Cas endonuclease family, plays a critical role in recognizing and cleaving foreign DNA. Phages, in retaliation, have evolved anti-CRISPR (Acr) proteins to disable the…
https://bioengineer.org/anti-crispr-sparks-cas12-mrna-decay/
info
“The discovery appears to be the first of its kind: one protein interrupting the manufacture of another on ribosomes.”
SINGLE SOURCE
The claim that this is the 'first of its kind' is a qualitative assessment made by the researchers in the study; it is not independently verified by other sources as a historical first in all of biology.
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web search NEUTRAL — Ribosome biogenesis is the process of making ribosomes. This is an energy-consuming, dynamic process, requiring the synthesis of around 200 proteins in the processing of ribosomal RNAs and assembling …
https://en.wikipedia.org/wiki/Ribosome
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web search NEUTRAL — This 3D animation shows how proteins are made in the cell from the information in the DNA code.
https://www.youtube.com/watch?v=gG7uCskUOrA
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web search NEUTRAL — So, for instance, she separated the ribosomes in one fraction and some other stuff in a different fraction. When she mixed the right components she could get the ribosomes to finish making what they w…
https://thebumblingbiochemist.com/365-days-of-science/hildeg…
help
“Nicole D. Marino et al, Translation-dependent degradation of cas12 mRNA triggered by an anti-CRISPR, Nature (2026). DOI: 10.1038/s41586-026-10440-8”
INSUFFICIENT EVIDENCE
No evidence was found in the provided search results to confirm the specific publication date of 2026 or the exact DOI provided, as the search results did not return the full bibliographic record for this specific paper.
info Disclaimer: This analysis is generated by AI and should be used as a starting point for critical thinking, not as definitive truth. Claims are verified against publicly available sources. Always consult the original article and additional sources for complete context.