4QR2

Crystal structure of Streptococcus pyogenes Cas2 at pH 7.5

Summary for 4QR2

• Entry DOI: 10.2210/pdb4qr2/pdb
• Related: 4QR0 4QR1
• Descriptor: CRISPR-associated endoribonuclease Cas2 (2 entities in total)
• Functional Keywords: ferredoxin-like fold, deoxyribonuclease, hydrolase
• Biological source: Streptococcus pyogenes serotype M1
• Total number of polymer chains: 2
• Total formula weight: 22523.86

Authors

Bae, E.,Ka, D.,Kim, D. (deposition date: 2014-06-30, release date: 2014-11-26, Last modification date: 2023-11-08)

Primary citation

Ka, D.,Kim, D.,Baek, G.,Bae, E.
Structural and functional characterization of Streptococcus pyogenes Cas2 protein under different pH conditions
Biochem.Biophys.Res.Commun., 451:152-157, 2014

PubMed Abstract: Clustered regularly interspaced short palindromic repeats (CRISPRs) and CRISPR-associated (Cas) proteins constitute an RNA-guided microbial defense system against invading foreign genetic materials. Cas2 is one of the core Cas proteins found universally in all the subtypes of CRISPR-Cas systems and is required for incorporating new spacers into CRISPR loci. Cas2 homologues from different CRISPR-Cas subtypes were characterized previously as metal-dependent nucleases with different substrate preferences, and it was proposed that a pH-dependent conformational change mediates metal binding and catalysis. Here, we report the crystal structures of Streptococcus pyogenes Cas2 at three different pHs (5.6, 6.5, and 7.5), as well as the results of its nuclease activity assay against double-stranded DNAs at varying pHs (6.0-9.0). Although S. pyogenes Cas2 exhibited strongly pH-dependent catalytic activity, there was no significant conformational difference among the three crystal structures. However, structural comparisons with other Cas2 homologues revealed structural variability and the flexible nature of its putative hinge regions, supporting the hypothesis that conformational switching is important for catalysis. Taken together, our results confirm that Cas2 proteins have pH-dependent nuclease activity against double-stranded DNAs, and provide indirect structural evidence for their conformational changes.

PubMed: 25079131
DOI: 10.1016/j.bbrc.2014.07.087

Experimental method

X-RAY DIFFRACTION (1.8 Å)