Toroidal Structure and DNA Cleavage by the CRISPR-Associated [4Fe-4S] Cluster Containing Cas4 Nuclease SSO0001 from Sulfolobus solfataricus

Cas4 proteins, a core protein family associated with the microbial system of adaptive immunity CRISPR, are predicted to function in the adaptation step of the CRISPR mechanism. Here we show that the Cas4 protein SSO0001 from the archaeon Sulfolobus solfataricus has metal-dependent endonuclease and 5...

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Bibliographic Details
Published in:	Journal of the American Chemical Society 2013-11, Vol.135 (46), p.17476-17487
Main Authors:	Lemak, Sofia, Beloglazova, Natalia, Nocek, Boguslaw, Skarina, Tatiana, Flick, Robert, Brown, Greg, Popovic, Ana, Joachimiak, Andrzej, Savchenko, Alexei, Yakunin, Alexander F
Format:	Article
Language:	eng
Subjects:	Archaeal Proteins - chemistry Archaeal Proteins - metabolism Clustered Regularly Interspaced Short Palindromic Repeats DNA - chemistry DNA - metabolism DNA Cleavage Iron-Sulfur Proteins - chemistry Iron-Sulfur Proteins - metabolism Models, Molecular Protein Conformation Sulfolobus solfataricus - enzymology
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Summary:	Cas4 proteins, a core protein family associated with the microbial system of adaptive immunity CRISPR, are predicted to function in the adaptation step of the CRISPR mechanism. Here we show that the Cas4 protein SSO0001 from the archaeon Sulfolobus solfataricus has metal-dependent endonuclease and 5′→3′ exonuclease activities against single-stranded DNA, as well as ATP-independent DNA unwinding activity toward double-stranded DNA. The crystal structure of SSO0001 revealed a decameric toroid formed by five dimers with each protomer containing one [4Fe-4S] cluster and one Mn2+ ion bound in the active site located inside the internal tunnel. The conserved RecB motif and four Cys residues are important for DNA binding and cleavage activities, whereas DNA unwinding depends on several residues located near the [4Fe-4S] cluster. Our results suggest that Cas4 proteins might contribute to the addition of novel CRISPR spacers through the formation of 3′-DNA overhangs and to the degradation of foreign DNA.
ISSN:	0002-7863 1520-5126