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Crystal structure of human DEAD-box RNA helicase DDX21 at post-hydrolysis stateCrystal structure of human DEAD-box RNA helicase DDX21 at post-hydrolysis state
Structural highlights
Function[DDX21_HUMAN] RNA helicase that acts as a sensor of the transcriptional status of both RNA polymerase (Pol) I and II: promotes ribosomal RNA (rRNA) processing and transcription from polymerase II (Pol II) (PubMed:25470060). Binds various RNAs, such as rRNAs, snoRNAs, 7SK and, at lower extent, mRNAs (PubMed:25470060). In the nucleolus, localizes to rDNA locus, where it directly binds rRNAs and snoRNAs, and promotes rRNA transcription, processing and modification. Required for rRNA 2'-O-methylation, possibly by promoting the recruitment of late-acting snoRNAs SNORD56 and SNORD58 with pre-ribosomal complexes (PubMed:25470060, PubMed:25477391). In the nucleoplasm, binds 7SK RNA and is recruited to the promoters of Pol II-transcribed genes: acts by facilitating the release of P-TEFb from inhibitory 7SK snRNP in a manner that is dependent on its helicase activity, thereby promoting transcription of its target genes (PubMed:25470060). Functions as cofactor for JUN-activated transcription: required for phosphorylation of JUN at 'Ser-77' (PubMed:11823437, PubMed:25260534). Can unwind double-stranded RNA (helicase) and can fold or introduce a secondary structure to a single-stranded RNA (foldase) (PubMed:9461305). Involved in rRNA processing (PubMed:14559904, PubMed:18180292).[1] [2] [3] [4] [5] [6] [7] Publication Abstract from PubMedRNA helicase DDX21 plays vital roles in ribosomal RNA biogenesis, transcription, and the regulation of host innate immunity during virus infection. How DDX21 recognizes and unwinds RNA and how DDX21 interacts with virus remain poorly understood. Here, crystal structures of human DDX21 determined in three distinct states are reported, including the apo-state, the AMPPNP plus single-stranded RNA (ssRNA) bound pre-hydrolysis state, and the ADP-bound post-hydrolysis state, revealing an open to closed conformational change upon RNA binding and unwinding. The core of the RNA unwinding machinery of DDX21 includes one wedge helix, one sensor motif V and the DEVD box, which links the binding pockets of ATP and ssRNA. The mutant D339H/E340G dramatically increases RNA binding activity. Moreover, Hill coefficient analysis reveals that DDX21 unwinds double-stranded RNA (dsRNA) in a cooperative manner. Besides, the nonstructural (NS1) protein of influenza A inhibits the ATPase and unwinding activity of DDX21 via small RNAs, which cooperatively assemble with DDX21 and NS1. The structures illustrate the dynamic process of ATP hydrolysis and RNA unwinding for RNA helicases, and the RNA modulated interaction between NS1 and DDX21 generates a fresh perspective toward the virus-host interface. It would benefit in developing therapeutics to combat the influenza virus infection. Structural Basis of Human Helicase DDX21 in RNA Binding, Unwinding, and Antiviral Signal Activation.,Chen Z, Li Z, Hu X, Xie F, Kuang S, Zhan B, Gao W, Chen X, Gao S, Li Y, Wang Y, Qian F, Ding C, Gan J, Ji C, Xu XW, Zhou Z, Huang J, He HH, Li J Adv Sci (Weinh). 2020 Jun 8;7(14):2000532. doi: 10.1002/advs.202000532., eCollection 2020 Jul. PMID:32714761[8] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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