CRISPR-Cas System
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CRISPRs extending their reach: prokaryotic RNAi protein Cas9 recruited for gene regulation : Article : The EMBO Journal

CRISPRs extending their reach: prokaryotic RNAi protein Cas9 recruited for gene regulation : Article : The EMBO Journal | CRISPR-Cas System | Scoop.it
A Cas protein from the CRISPR defence system against foreign DNA, also functions in endogenous gene regulation. Sampson et al (2013) have revealed that in pathogenic Francisella bacteria, the Cas9 protein guided by small RNAs represses the mRNA of a lipoprotein. This novel mechanism of post-transcriptional regulation enables the infecting bacteria to evade the TLR2-based innate immune response of its host. Thus, reminiscent of eukaryotic RNAi where some proteins facilitate both genome defence and gene regulation, a central prokaryotic RNAi protein not only destroys invading DNA but also controls mRNA expression.
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Clem Stanyon's curator insight, June 17, 2013 4:18 AM

Many years ago, I attended a seminar given by one of the leaders in mouse genome manipulation, who had been experimenting with alternative ways to get foreign DNA inside an egg. As something of an aside, which often happens in science, his team discovered that inhibition of reverse transcriptase - that which makes DNA from RNA, which is the opposite direction to what normally happens and what retroviruses do in order to hijack infected cells - aborts development if that inhibition occurs before the 4-cell stage. This pretty much demonstrated that modifications of genomic DNA structure are essential to the initiation of new life in mammalian cells.

This is a parallel circumstance, indicating that things involved in genome defense can also be involved in gene regulation, and begs the question of whether there is any real difference: to the protein involved, Cas9, the ultimate cellular outcome is not the issue; the issue is the basic enzymatic activity.

Clem Stanyon's comment, June 17, 2013 4:21 AM
Here's an article about the wider field, apropos of the protein fold that is involved in the larger family of enzymes, which are all involved with variations on the same higher-structural field:
http://7thspace.com/headlines/439526/comprehensive_analysis_of_the_hepn_superfamily_identification_of_novel_roles_in_intra_genomic_conflicts_defense_pathogenesis_and_rna_processing.html
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Powerful gene-editing tool appears to cause off-target mutations in human cells

Powerful gene-editing tool appears to cause off-target mutations in human cells | CRISPR-Cas System | Scoop.it

A team of Massachusetts General Hospital researchers has found a significant limitation to the use of CRISPR-Cas RGNs, production of unwanted DNA mutations at sites other than the desired target, which indicates a need to improve the specificity of...

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