Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.26.4 (RNase H)
 2,751 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Crystallization and preliminary crystallographic studies of type 1 RNase H from the hyperthermophilic archaeon Sulfolobus tokodaii 7 were performed. A crystal was grown at 277 K by the sitting-drop vapour-diffusion method. Native X-ray diffraction data were collected to 1.5 angstroms resolution using synchrotron radiation from station BL41XU at SPring-8. The crystal belongs to space group P4(3), with unit-cell parameters a = b = 39.21, c = 91.15 angstroms. Assuming the presence of one molecule in the asymmetric unit, the Matthews coefficient V(M) was calculated to be 2.1 angstroms3 Da(-1) and the solvent content was 40.5%. The structure of a selenomethionine Sto-RNase HI mutant obtained using a MAD data set is currently being analysed.
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PMID:Crystallization and preliminary crystallographic analysis of type 1 RNase H from the hyperthermophilic archaeon Sulfolobus tokodaii 7. 1688 May 56

The crystal structures of protein-nucleic acid complexes are commonly determined using selenium-derivatized proteins via MAD or SAD phasing. Here, the first protein-nucleic acid complex structure determined using selenium-derivatized nucleic acids is reported. The RNase H-RNA/DNA complex is used as an example to demonstrate the proof of principle. The high-resolution crystal structure indicates that this selenium replacement results in a local subtle unwinding of the RNA/DNA substrate duplex, thereby shifting the RNA scissile phosphate closer to the transition state of the enzyme-catalyzed reaction. It was also observed that the scissile phosphate forms a hydrogen bond to the water nucleophile and helps to position the water molecule in the structure. Consistently, it was discovered that the substitution of a single O atom by a Se atom in a guide DNA sequence can largely accelerate RNase H catalysis. These structural and catalytic studies shed new light on the guide-dependent RNA cleavage.
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PMID:Novel complex MAD phasing and RNase H structural insights using selenium oligonucleotides. 2453 69