3CDI

Crystal structure of E. coli PNPase


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.60 Å
  • R-Value Free: 0.277 
  • R-Value Work: 0.232 
  • R-Value Observed: 0.277 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history


Literature

Crystal structure of Escherichia coli PNPase: central channel residues are involved in processive RNA degradation.

Shi, Z.Yang, W.Z.Lin-Chao, S.Chak, K.F.Yuan, H.S.

(2008) RNA 14: 2361-2371

  • DOI: 10.1261/rna.1244308
  • Structures With Same Primary Citation

  • PubMed Abstract: 
  • Bacterial polynucleotide phosphorylase (PNPase) plays a major role in mRNA turnover by the degradation of RNA from the 3'- to 5'-ends. Here, we determined the crystal structures of the wild-type and a C-terminal KH/S1 domain-truncated mutant (DeltaKH ...

    Bacterial polynucleotide phosphorylase (PNPase) plays a major role in mRNA turnover by the degradation of RNA from the 3'- to 5'-ends. Here, we determined the crystal structures of the wild-type and a C-terminal KH/S1 domain-truncated mutant (DeltaKH/S1) of Escherichia coli PNPase at resolutions of 2.6 A and 2.8 A, respectively. The six RNase PH domains of the trimeric PNPase assemble into a ring-like structure containing a central channel. The truncated mutant DeltaKH/S1 bound and cleaved RNA less efficiently with an eightfold reduced binding affinity. Thermal melting and acid-induced trimer dissociation studies, analyzed by circular dichroism and dynamic light scattering, further showed that DeltaKH/S1 formed a less stable trimer than the full-length PNPase. The crystal structure of DeltaKH/S1 is more expanded, containing a slightly wider central channel than that of the wild-type PNPase, suggesting that the KH/S1 domain helps PNPase to assemble into a more compact trimer, and it regulates the channel size allosterically. Moreover, site-directed mutagenesis of several arginine residues in the channel neck regions produced defective PNPases that either bound and cleaved RNA less efficiently or generated longer cleaved oligonucleotide products, indicating that these arginines were involved in RNA binding and processive degradation. Taking these results together, we conclude that the constricted central channel and the basic-charged residues in the channel necks of PNPase play crucial roles in trapping RNA for processive exonucleolytic degradation.


    Organizational Affiliation

    Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan, Republic of China.



Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Polynucleotide phosphorylaseA723Escherichia coliMutation(s): 0 
Gene Names: pnp
EC: 2.7.7.8
Find proteins for P05055 (Escherichia coli (strain K12))
Explore P05055 
Go to UniProtKB:  P05055
Protein Feature View
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.60 Å
  • R-Value Free: 0.277 
  • R-Value Work: 0.232 
  • R-Value Observed: 0.277 
  • Space Group: F 41 3 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 270.118α = 90
b = 270.118β = 90
c = 270.118γ = 90
Software Package:
Software NamePurpose
HKL-2000data collection
CNSrefinement
HKL-2000data reduction
HKL-2000data scaling
CNSphasing

Structure Validation

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Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2008-12-09
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance