4DB4

Mss116p DEAD-box helicase domain 2 bound to a chimaeric RNA-DNA duplex


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.599 Å
  • R-Value Free: 0.280 
  • R-Value Work: 0.245 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Structural basis for RNA-duplex recognition and unwinding by the DEAD-box helicase Mss116p.

Mallam, A.L.Del Campo, M.Gilman, B.Sidote, D.J.Lambowitz, A.M.

(2012) Nature 490: 121-125

  • DOI: 10.1038/nature11402
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • DEAD-box proteins are the largest family of nucleic acid helicases, and are crucial to RNA metabolism throughout all domains of life. They contain a conserved 'helicase core' of two RecA-like domains (domains (D)1 and D2), which uses ATP to catalyse ...

    DEAD-box proteins are the largest family of nucleic acid helicases, and are crucial to RNA metabolism throughout all domains of life. They contain a conserved 'helicase core' of two RecA-like domains (domains (D)1 and D2), which uses ATP to catalyse the unwinding of short RNA duplexes by non-processive, local strand separation. This mode of action differs from that of translocating helicases and allows DEAD-box proteins to remodel large RNAs and RNA-protein complexes without globally disrupting RNA structure. However, the structural basis for this distinctive mode of RNA unwinding remains unclear. Here, structural, biochemical and genetic analyses of the yeast DEAD-box protein Mss116p indicate that the helicase core domains have modular functions that enable a novel mechanism for RNA-duplex recognition and unwinding. By investigating D1 and D2 individually and together, we find that D1 acts as an ATP-binding domain and D2 functions as an RNA-duplex recognition domain. D2 contains a nucleic-acid-binding pocket that is formed by conserved DEAD-box protein sequence motifs and accommodates A-form but not B-form duplexes, providing a basis for RNA substrate specificity. Upon a conformational change in which the two core domains join to form a 'closed state' with an ATPase active site, conserved motifs in D1 promote the unwinding of duplex substrates bound to D2 by excluding one RNA strand and bending the other. Our results provide a comprehensive structural model for how DEAD-box proteins recognize and unwind RNA duplexes. This model explains key features of DEAD-box protein function and affords a new perspective on how the evolutionarily related cores of other RNA and DNA helicases diverged to use different mechanisms.


    Organizational Affiliation

    Institute for Cellular and Molecular Biology, Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure


Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
ATP-dependent RNA helicase MSS116, mitochondrial
A, B
256Saccharomyces cerevisiae (strain ATCC 204508 / S288c)Mutation(s): 0 
Gene Names: MSS116
EC: 3.6.4.13
Find proteins for P15424 (Saccharomyces cerevisiae (strain ATCC 204508 / S288c))
Go to UniProtKB:  P15424
Entity ID: 2
MoleculeChainsLengthOrganism
5'-R(*GP*GP*GP*CP*GP*GP*G)-D(P*CP*CP*CP*GP*CP*CP*C)-3'C,D,E,F14N/A
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.599 Å
  • R-Value Free: 0.280 
  • R-Value Work: 0.245 
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 43.696α = 90.00
b = 70.112β = 90.00
c = 214.661γ = 90.00
Software Package:
Software NamePurpose
PHASERphasing
StructureStudiodata collection
HKL-2000data reduction
PHENIXrefinement
HKL-2000data scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2012-08-29
    Type: Initial release
  • Version 1.1: 2012-09-19
    Type: Database references
  • Version 1.2: 2012-10-10
    Type: Database references, Derived calculations