Alanine-glyoxylate aminotransferase 1 (AGT1) from Arabidopsis thaliana

Experimental Data Snapshot

  • Resolution: 2.18 Å
  • R-Value Free: 0.170 
  • R-Value Work: 0.139 
  • R-Value Observed: 0.141 

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Crystal Structure Of Photorespiratory Alanine:Glyoxylate Aminotransferase 1 (AGT1) FromArabidopsis thaliana.

Liepman, A.H.Vijayalakshmi, J.Peisach, D.Hulsebus, B.Olsen, L.J.Saper, M.A.

(2019) Front Plant Sci 10: 1229-1229

  • DOI: https://doi.org/10.3389/fpls.2019.01229
  • Primary Citation of Related Structures:  
    6PK1, 6PK3

  • PubMed Abstract: 

    Photorespiration is an energetically costly metabolic pathway for the recycling of phosphoglycolate produced by the oxygenase activity of ribulose-1,5-bisphosphate carboxylase/oxygenase (RUBISCO) to phosphoglycerate. Arabidopsis alanine:glyoxylate aminotransferase 1 (AGT1) is a peroxisomal aminotransferase with a central role in photorespiration. This enzyme catalyzes various aminotransferase reactions, including serine:glyoxylate, alanine:glyoxylate, and asparagine:glyoxylate transaminations. To better understand structural features that govern the specificity of this enzyme, its crystal structures in the native form (2.2-Å resolution) and in the presence of l-serine (2.1-Å resolution) were solved. The structures confirm that this enzyme is dimeric, in agreement with studies of the active enzyme in solution. In the crystal, another dimer related by noncrystallographic symmetry makes close interactions to form a tetramer mediated in part by an extra carboxyl-terminal helix conserved in plant homologs of AGT1. Pyridoxal 5'-phosphate (PLP) is bound at the active site but is not held in place by covalent interactions. Residues Tyr35' and Arg36', entering the active site from the other subunits in the dimer, mediate interactions between AGT and l-serine when used as a substrate. In comparison, AGT1 from humans and AGT1 from Anabaena lack these two residues and instead position a tyrosine ring into the binding site, which accounts for their preference for l-alanine instead of l-serine. The structure also rationalizes the phenotype of the sat mutant, Pro251 to Leu, which likely affects the dimer interface near the catalytic site. This structural model of AGT1 provides valuable new information about this protein that may enable improvements to the efficiency of photorespiration.

  • Organizational Affiliation

    Biology Department, Eastern Michigan University, Ypsilanti, MI, United States.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Serine--glyoxylate aminotransferase
A, B
401Arabidopsis thalianaMutation(s): 0 
Gene Names: AGT1At2g13360F14O4.7
EC: (PDB Primary Data), (PDB Primary Data), 2.6.1 (PDB Primary Data), (PDB Primary Data)
Find proteins for Q56YA5 (Arabidopsis thaliana)
Explore Q56YA5 
Go to UniProtKB:  Q56YA5
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ56YA5
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.18 Å
  • R-Value Free: 0.170 
  • R-Value Work: 0.139 
  • R-Value Observed: 0.141 
  • Space Group: P 21 21 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 139.179α = 90
b = 62.289β = 90
c = 97.013γ = 90
Software Package:
Software NamePurpose
PDB_EXTRACTdata extraction
SCALEPACKdata scaling
DENZOdata reduction

Structure Validation

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Ligand Structure Quality Assessment 

Entry History & Funding Information

Deposition Data

Funding OrganizationLocationGrant Number
National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)United StatesNIH-GM08353

Revision History  (Full details and data files)

  • Version 1.0: 2019-10-23
    Type: Initial release
  • Version 1.1: 2019-11-20
    Changes: Database references
  • Version 1.2: 2020-01-01
    Changes: Author supporting evidence
  • Version 1.3: 2024-03-13
    Changes: Data collection, Database references