CRISPR-Cas adaptive immune systems of the sulfolobales: unravelling their complexity and diversity

Roger Antony Garrett, Shiraz Ali Shah, Susanne Erdmann, Liu Guannan, Marzieh Mousaei, Carlos León Sobrino, Wenfang Peng, Sóley Ruth Islin, Ling Deng, Gisle Vestergaard, Xu Peng, Qunxin She

Research output: Contribution to journalJournal articleResearchpeer-review

42 Citations (Scopus)
381 Downloads (Pure)

Abstract

The Sulfolobales have provided good model organisms for studying CRISPR-Cas systems of the crenarchaeal kingdom of the archaea. These organisms are infected by a wide range of exceptional archaea-specific viruses and conjugative plasmids, and their CRISPR-Cas systems generally exhibit extensive structural and functional diversity. They carry large and multiple CRISPR loci and often multiple copies of diverse Type I and Type III interference modules as well as more homogeneous adaptation modules. These acidothermophilic organisms have recently provided seminal insights into both the adaptation process, the diverse modes of interference, and their modes of regulation. The functions of the adaptation and interference modules tend to be loosely coupled and the stringency of the crRNA-DNA sequence matching during DNA interference is relatively low, in contrast to some more streamlined CRISPR-Cas systems of bacteria. Despite this, there is evidence for a complex and differential regulation of expression of the diverse functional modules in response to viral infection. Recent work also supports critical roles for non-core Cas proteins, especially during Type III-directed interference, and this is consistent with these proteins tending to coevolve with core Cas proteins. Various novel aspects of CRISPR-Cas systems of the Sulfolobales are considered including an alternative spacer acquisition mechanism, reversible spacer acquisition, the formation and significance of antisense CRISPR RNAs, and a novel mechanism for avoidance of CRISPR-Cas defense. Finally, questions regarding the basis for the complexity, diversity, and apparent redundancy, of the intracellular CRISPR-Cas systems are discussed.
Original languageEnglish
JournalLife
Volume5
Issue number1
Pages (from-to)783-817
Number of pages35
ISSN2075-1729
DOIs
Publication statusPublished - 2015

Cite this