Crystal structure of human RNA helicase A (DHX9: structural basis for unselective nucleotide base binding in a DEAD-box variant protein
2010 (English)In: Journal of Molecular Biology, ISSN 0022-2836, E-ISSN 1089-8638, Vol. 400, no 4, 768-782 p.Article in journal (Refereed) Published
RNA helicases of the DExD/H-box superfamily are critically involved in all RNA-related processes. No crystal structures of human DExH-box domains had been determined previously, and their structures were difficult to predict owing to the low level of homology among DExH-motif-containing proteins from diverse species. Here we present the crystal structures of the conserved domain 1 of the DEIH-motif-containing helicase DHX9 and of the DEAD-box helicase DDX20. Both contain a RecA-like core, but DHX9 differs from DEAD-box proteins in the arrangement of secondary structural elements and is more similar to viral helicases such as NS3. The N-terminus of the DHX9 core contains two long alpha-helices that reside on the surface of the core without contributing to nucleotide binding. The RNA-polymerase-II-interacting minimal transactivation domain sequence forms an extended loop structure that resides in a hydrophobic groove on the surface of the DEIH domain. DHX9 lacks base-selective contacts and forms an unspecific but important stacking interaction with the base of the bound nucleotide, and our biochemical analysis confirms that the protein can hydrolyze ATP, guanosine 5'-triphosphate, cytidine 5'-triphosphate, and uridine 5'-triphosphate. Together, these findings allow the localization of functional motifs within the three-dimensional structure of a human DEIH helicase and show how these enzymes can bind nucleotide with high affinity in the absence of a Q-motif.
Place, publisher, year, edition, pages
Elsevier, 2010. Vol. 400, no 4, 768-782 p.
RNA helicase; RecA; DExD/H-box; nucleotide binding; X-ray crystallography
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:liu:diva-76053DOI: 10.1016/j.jmb.2010.05.046PubMedID: 20510246OAI: oai:DiVA.org:liu-76053DiVA: diva2:511937