Mechanism of foreign DNA recognition by a CRISPR RNA-guided surveillance complex from Pseudomonas aeruginosa.
Nucleic Acids Res
; 43(4): 2216-22, 2015 Feb 27.
Article
em En
| MEDLINE
| ID: mdl-25662606
ABSTRACT
The Type I-F CRISPR-mediated (clustered regularly interspaced short palindromic repeats) adaptive immune system in Pseudomonas aeruginosa consists of two CRISPR loci and six CRISPR-associated (cas) genes. Foreign DNA surveillance is performed by a complex of Cas proteins (Csy14) that assemble with a CRISPR RNA (crRNA) into a 350-kDa ribonucleoprotein called the Csy complex. Here, we show that foreign nucleic acid recognition by the Csy complex proceeds through sequential steps, initiated by detection of two consecutive guaninecytosine base pairs (GC/GC) located adjacent to the complementary DNA target. We show that this motif, called the PAM (protospacer adjacent motif), must be double-stranded and that single-stranded PAMs do not provide significant discriminating power. Binding assays performed with GC/GC-rich competitor sequences indicate that the Csy complex interacts directly with this dinucleotide motif, and kinetic analyses reveal that recognition of a GC/GC motif is a prerequisite for crRNA-guided binding to a target sequence. Together, these data indicate that the Csy complex first interacts with GC/GC base pairs and then samples adjacent target sequences for complementarity to the crRNA guide.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Pseudomonas aeruginosa
/
DNA
/
RNA Bacteriano
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Proteínas Associadas a CRISPR
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Sistemas CRISPR-Cas
Tipo de estudo:
Screening_studies
Idioma:
En
Ano de publicação:
2015
Tipo de documento:
Article