Major bacterial lineages are essentially devoid of CRISPR-Cas viral defence systems.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 26837824.
- Also identified by DOI 10.1038/ncomms10613 and PMC identifier 4742961.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Current understanding of microorganism-virus interactions, which shape the evolution and functioning of Earth's ecosystems, is based primarily on cultivated organisms. Here we investigate thousands of viral and microbial genomes recovered using a cultivation-independent approach to study the frequency, variety and taxonomic distribution of viral defence mechanisms. CRISPR-Cas systems that confer microorganisms with immunity to viruses are present in only 10% of 1,724 sampled microorganisms, compared with previous reports of 40% occurrence in bacteria and 81% in archaea. We attribute this large difference to the lack of CRISPR-Cas systems across major bacterial lineages that have no cultivated representatives. We correlate absence of CRISPR-Cas with lack of nucleotide biosynthesis capacity and a symbiotic lifestyle. Restriction systems are well represented in these lineages and might provide both non-specific viral defence and access to nucleotides.
Medical subject headings
- Bacteria
- CRISPR-Cas Systems
- Genome, Bacterial
- Genome, Viral
- Symbiosis
- Viruses