Format

Send to

Choose Destination
Nucleic Acids Res. 2015 Dec 15;43(22):10576-87. doi: 10.1093/nar/gkv1180. Epub 2015 Nov 16.

The casposon-encoded Cas1 protein from Aciduliprofundum boonei is a DNA integrase that generates target site duplications.

Author information

1
Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
2
Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA Fred.Dyda@nih.gov.

Abstract

Many archaea and bacteria have an adaptive immune system known as CRISPR which allows them to recognize and destroy foreign nucleic acid that they have previously encountered. Two CRISPR-associated proteins, Cas1 and Cas2, are required for the acquisition step of adaptation, in which fragments of foreign DNA are incorporated into the host CRISPR locus. Cas1 genes have also been found scattered in several archaeal and bacterial genomes, unassociated with CRISPR loci or other cas proteins. Rather, they are flanked by nearly identical inverted repeats and enclosed within direct repeats, suggesting that these genetic regions might be mobile elements ('casposons'). To investigate this possibility, we have characterized the in vitro activities of the putative Cas1 transposase ('casposase') from Aciduliprofundum boonei. The purified Cas1 casposase can integrate both short oligonucleotides with inverted repeat sequences and a 2.8 kb excised mini-casposon into target DNA. Casposon integration occurs without target specificity and generates 14-15 basepair target site duplications, consistent with those found in casposon host genomes. Thus, Cas1 casposases carry out similar biochemical reactions as the CRISPR Cas1-Cas2 complex but with opposite substrate specificities: casposases integrate specific sequences into random target sites, whereas CRISPR Cas1-Cas2 integrates essentially random sequences into a specific site in the CRISPR locus.

PMID:
26573596
PMCID:
PMC4678821
DOI:
10.1093/nar/gkv1180
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Silverchair Information Systems Icon for PubMed Central
Loading ...
Support Center