Episode Summary

Large phage discovered that contains a compact version of the CRISPR/Cas defense/gene editing system!

Microbe of the episode

Microbe of the episode: Stenotrophomonas virus IME13

Jesse's takeaways

CRISPR/Cas systems have made a lot of things in gene editing much easier in certain organisms. It's almost as easy as just getting the cells to produce the Cas protein and putting in an RNA sequence to tell it where to go! But in some cases, these requirements are too much to work well.
In this study, a more compact version of CRISPR/Cas was discovered in large bacteriophages. These systems help the viruses compete with other viruses and defend against host defenses sometimes. The Cas protein is half the size of the standard Cas most used in gene editing, and it has fewer other requirements to function in new cells, so it could be better in versatility and potential in applications with strict space constraints.


Megaphages harbor mini-Cas proteins ideal for gene editing

Journal Paper

Pausch P, Al-Shayeb B, Bisom-Rapp E, Tsuchida CA, Li Z, Cress BF, Knott GJ, Jacobsen SE, Banfield JF, Doudna JA. 2020. CRISPR-CasΦ from huge phages is a hypercompact genome editor. Science 369:333–337.

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BacterioFiles episode thumbnail featuring T4 bacteriophage