Structural basis for DNA duplex separation by a superfamily-2 helicase
| Autor: | Karl-Peter Hopfner, Sebastian Nehring, Katharina Büttner |
|---|---|
| Rok vydání: | 2007 |
| Předmět: |
Protein Conformation
Base pair Archaeal Proteins viruses Molecular Sequence Data Crystallography X-Ray Adenosine Triphosphate Structural Biology Amino Acid Sequence Molecular Biology Polymerase Genetics Binding Sites DNA clamp Base Sequence biology Circular bacterial chromosome Helix-Loop-Helix Motifs DNA Helicases Helicase DNA RNA Helicase A Archaeoglobus fulgidus Coding strand biology.protein Biophysics DNA polymerase I |
| Zdroj: | Nature Structural & Molecular Biology. 14:647-652 |
| ISSN: | 1545-9985 1545-9993 |
| DOI: | 10.1038/nsmb1246 |
| Popis: | To reveal the mechanism of processive strand separation by superfamily-2 (SF2) 3'--5' helicases, we determined apo and DNA-bound crystal structures of archaeal Hel308, a helicase that unwinds lagging strands and is related to human DNA polymerase theta. Our structure captures the duplex-unwinding reaction, shows that initial strand separation does not require ATP and identifies a prominent beta-hairpin loop as the unwinding element. Similar loops in hepatitis C virus NS3 helicase and RNA-decay factors support the idea that this duplex-unwinding mechanism is applicable to a broad subset of SF2 helicases. Comparison with ATP-bound SF2 enzymes suggests that ATP promotes processive unwinding of 1 base pair by ratchet-like transport of the 3' product strand. Our results provide a first structural framework for strand separation by processive SF2 3'--5' helicases and reveal important mechanistic differences from SF1 helicases. |
| Databáze: | OpenAIRE |
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