Format

Send to

Choose Destination
PLoS One. 2012;7(7):e40913. doi: 10.1371/journal.pone.0040913. Epub 2012 Jul 20.

Cleavage of phage DNA by the Streptococcus thermophilus CRISPR3-Cas system.

Author information

1
Département de Biochimie, de Microbiologie et Bio-Informatiques, Faculté des Sciences et de Génie, Groupe de Recherche en Ecologie Buccale, Université Laval, Québec, Canada.

Abstract

Streptococcus thermophilus, similar to other Bacteria and Archaea, has developed defense mechanisms to protect cells against invasion by foreign nucleic acids, such as virus infections and plasmid transformations. One defense system recently described in these organisms is the CRISPR-Cas system (Clustered Regularly Interspaced Short Palindromic Repeats loci coupled to CRISPR-associated genes). Two S. thermophilus CRISPR-Cas systems, CRISPR1-Cas and CRISPR3-Cas, have been shown to actively block phage infection. The CRISPR1-Cas system interferes by cleaving foreign dsDNA entering the cell in a length-specific and orientation-dependant manner. Here, we show that the S. thermophilus CRISPR3-Cas system acts by cleaving phage dsDNA genomes at the same specific position inside the targeted protospacer as observed with the CRISPR1-Cas system. Only one cleavage site was observed in all tested strains. Moreover, we observed that the CRISPR1-Cas and CRISPR3-Cas systems are compatible and, when both systems are present within the same cell, provide increased resistance against phage infection by both cleaving the invading dsDNA. We also determined that overall phage resistance efficiency is correlated to the total number of newly acquired spacers in both CRISPR loci.

PMID:
22911717
PMCID:
PMC3401199
DOI:
10.1371/journal.pone.0040913
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Public Library of Science Icon for PubMed Central
Loading ...
Support Center