The immune system of halophilic archaea

Mobile Genetic Elements
Lisa-Katharina MaierAnita Marchfelder

Abstract

Prokaryotes have developed several strategies to defend themselves against foreign genetic elements. One of those defense mechanisms is the recently identified CRISPR/Cas system, which is used by approximately half of all bacterial and almost all archaeal organisms. The CRISPR/Cas system differs from the other defense strategies because it is adaptive, hereditary and it recognizes the invader by a sequence specific mechanism. To identify the invading foreign nucleic acid, a crRNA that matches the invader DNA is required, as well as a short sequence motif called protospacer adjacent motif (PAM). We recently identified the PAM sequences for the halophilic archaeon Haloferax volcanii, and found that several motifs were active in triggering the defense reaction. In contrast, selection of protospacers from the invader seems to be based on fewer PAM sequences, as evidenced by comparative sequence data. This suggests that the selection of protospacers has stricter requirements than the defense reaction. Comparison of CRISPR-repeat sequences carried by sequenced haloarchaea revealed that in more than half of the species, the repeat sequence is conserved and that they have the same CRISPR/Cas type.

References

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Citations

Feb 19, 2015·Life·Lisa-Katharina MaierAnita Marchfelder
Nov 18, 2014·Life·Alison W S LukR Cavicchioli
Mar 2, 2016·Environmental Microbiology Reports·Nina S AtanasovaHanna M Oksanen
Mar 24, 2017·Nucleic Acids Research·Aris-Edda StachlerUri Gophna
May 27, 2016·The Journal of Biological Chemistry·Aris-Edda Stachler, Anita Marchfelder
Nov 22, 2013·Biochemical Society Transactions·Britta StollAnita Marchfelder

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