An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
natural cavity, and variants with substitutions to polar residues to affect the state of hydratio... more natural cavity, and variants with substitutions to polar residues to affect the state of hydration of cavities to study its role in pressure unfolding. For 27 variants studied we obtained (a) crystal structures, (b) thermodynamic stabilities using chemical denaturation, and (c) DV of unfolding measured by pressure denaturation monitored with Trp fluorescence. DV of unfolding were also measured using NMR spectroscopy for select variants. The cavities generally did not affect the structure. Although large enough to hold several waters, water molecules were only detected in the cavities when lined with polar groups. The measured DV of variants was always larger than for the wild-type. A near-linear correlation between the DV measured experimentally and the one calculated from structures illustrates the importance of cavities in pressure sensitivity. A correlation between measured DV and thermodynamic stability (DG) suggests that 1 kcal/mol is lost per 12 mL/mol of increased void volume. This study demonstrates irrefutably the significant contributions cavities make towards the pressure sensitivity of proteins and their effects on internal hydration and structural fluctuations of proteins. Crystal Structures of Streptococcus Pyogenes Cas2 Protein at Various pH Conditions Ugeene Jeong. College of agricultural and life sciences, Seoul national university, Seoul, Korea, Republic of. Clustered regularly interspaced short palindromic repeats (CRISPRs) and CRISPR-associated (cas) proteins provide RNA-mediated adaptive immunity against foreign invading nucleic acids such as phages and plasmids in archaea and bacteria. Cas2 protein is one of the two core Cas proteins are present in all types of CRISPR-Cas systems and is required for new spacer integration into CRISPR loci. Cas2 homologues from several CRISPR-Cas subtypes were characterized 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 X-ray crystal structures of Streptococcus pyogenes Cas2 protein at three different pHs (5.6, 6.5, and 7.5), and the results of its nuclease activity assay at varying pHs (6.0-9.0). While 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 suggest structural variability and the flexible nature of its putative hinge regions, supporting the supposition that conformational change is important for catalysis.
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Papers by Ester Sesmero