Type III CRISPR-Cas systems can provide redundancy to counteract viral escape from type I systems.
CRISPR-Cas-mediated defense utilizes information stored as spacers in CRISPR arrays to defend against genetic invaders. We define the mode of target interference and role in antiviral defense for two CRISPR-Cas systems in Marinomonas mediterranea. One system (type I-F) targets DNA. A second system (type III-B) is broadly capable of acquiring spacers in either orientation from RNA and DNA, and exhibits transcription-dependent DNA interference. Examining resistance to phages isolated from Mediterranean seagrass meadows, we found that the type III-B machinery co-opts type I-F CRISPR-RNAs. Sequencing and infectivity assessments of related bacterial and phage strains suggests an 'arms race' in which phage escape from the type I-F system can be overcome through use of type I-F spacers by a horizontally-acquired type III-B system. We propose that the phage-host arms race can drive selection for horizontal uptake and maintenance of promiscuous type III interference modules that supplement existing host type I CRISPR-Cas systems.
['Silas|Sukrit|S|http://orcid.org/0000-0003-3251-8579', 'Lucas-Elio|Patricia|P|http://orcid.org/0000-0001-7182-1189', 'Jackson|Simon A|SA|http://orcid.org/0000-0002-4512-3093', 'Aroca-Crevillén|Alejandra|A|', 'Hansen|Loren L|LL|', 'Fineran|Peter C|PC|http://orcid.org/0000-0002-4639-6704', 'Fire|Andrew Z|AZ|http://orcid.org/0000-0001-6217-8312', 'Sánchez-Amat|Antonio|A|http://orcid.org/0000-0001-8597-9235']
D001435:Bacteriophages D001483:Base Sequence D064113:CRISPR-Cas Systems D064112:Clustered Regularly Interspaced Short Palindromic Repeats D004279:DNA, Viral D022761:Gene Transfer, Horizontal D053544:Marinomonas D010957:Plasmids D012367:RNA, Viral D000069177:Type I Secretion Systems D000069296:Type III Secretion Systems
CRISPR Marinomonas mediterranea phage phage-host arms race bacteria evolutionary biology genomics immunity infectious disease microbiology