Novel complex MAD phasing and RNase H structural insights using selenium oligonucleotides
- Georgia State University, Atlanta, GA 30303 (United States)
Selenium-derivatized oligonucleotides may facilitate phase determination and high-resolution structure determination for protein–nucleic acid crystallography. The Se atom-specific mutagenesis (SAM) strategy may also enhance the study of nuclease catalysis. 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.
- OSTI ID:
- 22351306
- Journal Information:
- Acta Crystallographica. Section D: Biological Crystallography, Journal Name: Acta Crystallographica. Section D: Biological Crystallography Journal Issue: Pt 2 Vol. 70; ISSN ABCRE6; ISSN 0907-4449
- Country of Publication:
- Denmark
- Language:
- English
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