Type III CRISPR-Cas Immunity: Major Differences Brushed Aside

• Autores: Gintautas Tamulaitis, Česlovas Venclovas, Virginijus Siksnys
• Localización: Trends in microbiology, ISSN 0966-842X, Vol. 25, Nº. 1, 2017, págs. 49-61
• Idioma: inglés
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• Resumen

  • For a long time the mechanism of immunity provided by the Type III CRISPR-Cas systems appeared to be inconsistent: the Type III-A Csm complex of Staphylococcus epidermidis was first reported to target DNA while Type III-B Cmr complexes were shown to target RNA. This long-standing conundrum has now been resolved by finding that the Type III CRISPR-Cas systems are both RNases and target RNA-activated DNA nucleases. The immunity is achieved by coupling binding and cleavage of RNA transcripts to the degradation of invading DNA. The base-pairing potential between the target RNA and the CRISPR RNA (crRNA) 5′-handle seems to play an important role in discriminating self and non-self nucleic acids; however, the detailed mechanism remains to be uncovered.