1YFS

The crystal structure of alanyl-tRNA synthetase in complex with L-alanine


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.08 Å
  • R-Value Free: 0.236 
  • R-Value Work: 0.189 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Breaking sieve for steric exclusion of a noncognate amino acid from active site of a tRNA synthetase.

Swairjo, M.A.Schimmel, P.R.

(2005) Proc.Natl.Acad.Sci.USA 102: 988-993

  • DOI: 10.1073/pnas.0409024102
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • The genetic code is fixed in aminoacylation reactions catalyzed by aminoacyl-tRNA synthetases. Amino acid discrimination occurs at two sites: one for amino acid activation and aminoacylation and one for editing misactivated amino acids. Although the ...

    The genetic code is fixed in aminoacylation reactions catalyzed by aminoacyl-tRNA synthetases. Amino acid discrimination occurs at two sites: one for amino acid activation and aminoacylation and one for editing misactivated amino acids. Although the active site sieves out bulkier amino acids, misactivation occurs with substrates whose side chains are smaller than the cognate one. Paradoxically, although alanyl-tRNA synthetase activates glycine as well as alanine, the sterically larger (than alanine) serine is also misactivated. Here, we report crystal structures of an active fragment of Aquifex aeolicus alanyl-tRNA synthetase complexed, separately, with Mg2+-ATP, alanine, glycine, and serine. Ala and Gly are bound in similar orientations in a side-chain-accommodating pocket, where alpha-amino and carboxyl groups are stabilized by salt bridges, and the carboxyl by an H-bond from the side chain NH2 of Asn-194. In contrast, whereas the same two salt bridges stabilize bound Ser, H-bonding of the highly conserved (among class II tRNA synthetases) Asn-194 side chain NH2 to the Ser OH, instead of to the carboxyl, forces pocket expansion. Significantly, in the Mg2+-ATP complex, Asn-194 coordinates a Mg2+-alpha-phosphate bridge. Thus, the sieve for Ser exclusion is broken because of selective pressure to retain Asn-194 for Mg2+-ATP and Ala binding.


    Related Citations: 
    • Alanyl-tRNA synthetase crystal structure and design for acceptor-stem recognition
      Swairjo, M.A.,Otero, F.J.,Yang, X.-L.,Lovato, M.A.,Skene, R.J.,McRee, D.E.,Ribas de Pouplana, L.,Schimmel, P.
      (2004) Mol.Cell 13: 829


    Organizational Affiliation

    The Skaggs Institute for Chemical Biology and Department of Molecular Biology, The Scripps Research Institute, BCC-379, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Alanyl-tRNA synthetase
A, B
465Aquifex aeolicus (strain VF5)Mutation(s): 0 
Gene Names: alaS
EC: 6.1.1.7
Find proteins for O67323 (Aquifex aeolicus (strain VF5))
Go to UniProtKB:  O67323
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
ALA
Query on ALA

Download SDF File 
Download CCD File 
A, B
ALANINE
C3 H7 N O2
QNAYBMKLOCPYGJ-REOHCLBHSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.08 Å
  • R-Value Free: 0.236 
  • R-Value Work: 0.189 
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 173.026α = 90.00
b = 73.868β = 90.00
c = 73.999γ = 90.00
Software Package:
Software NamePurpose
CNSphasing
SCALEPACKdata scaling
Blu-Icedata collection
CNSrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2005-01-25
    Type: Initial release
  • Version 1.1: 2008-04-30
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance