3WCO

Crystal structure of the depentamerized mutant of N-terminal truncated selenocysteine synthase SelA


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.40 Å
  • R-Value Free: 0.229 
  • R-Value Work: 0.179 
  • R-Value Observed: 0.181 

wwPDB Validation   3D Report Full Report


This is version 1.1 of the entry. See complete history


Literature

Dimer-Dimer Interaction of the Bacterial Selenocysteine Synthase SelA Promotes Functional Active-Site Formation and Catalytic Specificity

Itoh, Y.Brocker, M.J.Sekine, S.Soll, D.Yokoyama, S.

(2014) J Mol Biol 426: 1723-1735

  • DOI: 10.1016/j.jmb.2014.01.003
  • Primary Citation of Related Structures:  
    3WCN, 3WCO

  • PubMed Abstract: 
  • The 21st amino acid, selenocysteine (Sec), is incorporated translationally into proteins and is synthesized on its specific tRNA (tRNA(Sec)). In Bacteria, the selenocysteine synthase SelA converts Ser-tRNA(Sec), formed by seryl-tRNA synthetase, to Sec-tRNA(Sec) ...

    The 21st amino acid, selenocysteine (Sec), is incorporated translationally into proteins and is synthesized on its specific tRNA (tRNA(Sec)). In Bacteria, the selenocysteine synthase SelA converts Ser-tRNA(Sec), formed by seryl-tRNA synthetase, to Sec-tRNA(Sec). SelA, a member of the fold-type-I pyridoxal 5'-phosphate-dependent enzyme superfamily, has an exceptional homodecameric quaternary structure with a molecular mass of about 500kDa. Our previously determined crystal structures of Aquifex aeolicus SelA complexed with tRNA(Sec) revealed that the ring-shaped decamer is composed of pentamerized SelA dimers, with two SelA dimers arranged to collaboratively interact with one Ser-tRNA(Sec). The SelA catalytic site is close to the dimer-dimer interface, but the significance of the dimer pentamerization in the catalytic site formation remained elusive. In the present study, we examined the quaternary interactions and demonstrated their importance for SelA activity by systematic mutagenesis. Furthermore, we determined the crystal structures of "depentamerized" SelA variants with mutations at the dimer-dimer interface that prevent pentamerization. These dimeric SelA variants formed a distorted and inactivated catalytic site and confirmed that the pentamer interactions are essential for productive catalytic site formation. Intriguingly, the conformation of the non-functional active site of dimeric SelA shares structural features with other fold-type-I pyridoxal 5'-phosphate-dependent enzymes with native dimer or tetramer (dimer-of-dimers) quaternary structures.


    Organizational Affiliation

    Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan; RIKEN Systems and Structural Biology Center, 1-7-22 Suehiro-cho, Tsurumi, Yokohama 230-0045, Japan; RIKEN Structural Biology Laboratory, 1-7-22 Suehiro-cho, Tsurumi, Yokohama 230-0045, Japan. Electronic address: yokoyama@riken.jp.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
L-seryl-tRNA(Sec) selenium transferaseA, B392Aquifex aeolicus VF5Mutation(s): 4 
Gene Names: aq_1031selA
EC: 2.9.1.1
UniProt
Find proteins for O67140 (Aquifex aeolicus (strain VF5))
Explore O67140 
Go to UniProtKB:  O67140
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupO67140
Protein Feature View
Expand
  • Reference Sequence
Small Molecules
Modified Residues  2 Unique
IDChainsTypeFormula2D DiagramParent
LLP
Query on LLP
A, B L-PEPTIDE LINKINGC14 H22 N3 O7 PLYS
MSE
Query on MSE
A, B L-PEPTIDE LINKINGC5 H11 N O2 SeMET
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.40 Å
  • R-Value Free: 0.229 
  • R-Value Work: 0.179 
  • R-Value Observed: 0.181 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 59.19α = 90
b = 81.286β = 92.23
c = 95.537γ = 90
Software Package:
Software NamePurpose
PHENIXrefinement
PDB_EXTRACTdata extraction
ADSCdata collection
HKL-2000data reduction
HKL-2000data scaling
PHASERphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2014-01-22
    Type: Initial release
  • Version 1.1: 2014-04-30
    Changes: Database references