Diversity, Activity, and Evolution of CRISPR Loci in Streptococcus thermophilus

• DOI: 10.1128/jb.01415-07
• Publication Date: 2007-12-08T01:53:35Z
• Authors: Philippe Horvath; Dennis A. Romero; Anne-Claire Coût...; Melissa Richards; Hélène Deveau; Sylvain Moineau; Patrick Boyaval; Christophe Fremaux; Rodolphe Barrangou
• Keywords: Trans-activating crRNA; CRISPR interference

ABSTRACT Clustered regularly interspaced short palindromic repeats (CRISPR) are hypervariable loci widely distributed in prokaryotes that provide acquired immunity against foreign genetic elements. Here, we characterize a novel Streptococcus thermophilus locus, CRISPR3, and experimentally demonstrate its ability to integrate spacers response bacteriophage. Also, analyze CRISPR diversity activity across three distinct several S. strains. We show both cas genes locus specific functionally coupled. A total of 124 strains were studied, 109 unique spacer arrangements observed the loci. Overall, 3,626 analyzed, including 2,829 for CRISPR1 (782 unique), 173 CRISPR2 (16 624 CRISPR3 (154 unique). Sequence analysis revealed homology identity phage sequences (77%), plasmid (16%), chromosomal (7%). Polymorphisms repeats, spacers, genes, motif, architecture, sequence content. Interestingly, evolved via polarized addition after exposure elements internal deletion spacers. hypothesize level is correlated with relative propose highest CRISPR1, followed by while may be degenerate. Globally, dynamic nature might prove valuable typing comparative analyses microbial populations. CRISPRs critical insights into relationships between their environments, notably coevolution host viral genomes.