Diversity, classification and evolution of CRISPR-Cas systems

By Eugene V. Koonin, Kira S. Makarova, Feng Zhang. Current Opinion in Microbiology, 2017

1,234 citations recorded by the source corpus.

The bacterial and archaeal CRISPR-Cas systems of adaptive immunity show remarkable diversity of protein composition, effector complex structure, genome locus architecture and mechanisms of adaptation, pre-CRISPR (cr)RNA processing and interference. The CRISPR-Cas systems belong to two classes, with multi-subunit effector complexes in Class 1 and single-protein effector modules in Class 2. Concerted genomic and experimental efforts on comprehensive characterization of Class 2 CRISPR-Cas systems led to the identification of two new types and several subtypes. The newly characterized type VI systems are the first among the CRISPR-Cas variants to exclusively target RNA. Unexpectedly, in some of the class 2 systems, the effector protein is additionally responsible for the pre-crRNA processing. Comparative analysis of the effector complexes indicates that Class 2 systems evolved from mobile genetic elements on multiple, independent occasions.

Subfields: Genetics, Insect Science, Molecular Biology

View Paper: https://www.semanticscholar.org/paper/84ede3aa986255c827d00839d9f8123ac8f319a2

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Citations in the corpus

CRISPR/Cas Systems towards Next-Generation Biosensing. (2019, background): “Concluding Remarks and Future Perspectives Based on current understanding, the entirety of the discovered CRISPR/Cas family has been categorized into two classes with six subtypes [52,53].”
CRISPRCasFinder, an update of CRISRFinder, includes a portable version, enhanced performance and integrates search for Cas proteins (2018, background): “At last, using extra information can improve the ability to distinguish small CRISPRs from false positives, including the existence of a similar repeat in a larger CRISPR array, the presence of cas genes, generally situated upstream the CRISPR array (27) or of a characteristic leader sequence.”
CRISPR/Cas Genome Editing and Precision Plant Breeding in Agriculture. (2019, background): “The CRISPR system that has been developed for genome editing is based on RNA-guided interference with DNA (64).”
Transcriptome engineering with RNA-targeting Type VI-D CRISPR effectors (2018, neutral): “…systems are broadly divided into two classes, each with multiple types and subtypes: class 1 systems (types I and III) coordinate multiple proteins that cooperate for target surveillance and defense, while class 2 systems integrate both functions into a single effector enzyme (Koonin et al., 2017).”
The Biology of CRISPR-Cas: Backward and Forward. (2018, neutral): “The fusion of Cas4 to Cas1 in types I-U and V-B (Koonin et al., 2017; Mohanraju et al., 2016) and the formation of a complex containing Cas4, Cas1, Cas2, and Csa1 in Thermoproteus tenax (Plagens et al., 2012) is also suggestive of a role of Cas4 in adaptation.”