Gabaculien complex of gabaculine resistant GSAM version

Experimental Data Snapshot

  • Resolution: 2.35 Å
  • R-Value Free: 0.241 
  • R-Value Work: 0.208 
  • R-Value Observed: 0.208 

wwPDB Validation   3D Report Full Report

Ligand Structure Quality Assessment 

This is version 1.3 of the entry. See complete history


Absence of a catalytic water confers resistance to the neurotoxin gabaculine.

Orriss, G.L.Patel, T.R.Sorensen, J.Stetefeld, J.

(2010) FASEB J 24: 404-414

  • DOI: https://doi.org/10.1096/fj.09-138297
  • Primary Citation of Related Structures:  
    3FQ7, 3FQ8, 3FQA

  • PubMed Abstract: 

    Gabaculine is a potent inhibitor of the vitamin B6-dependent key enzyme in chlorophyll biosynthesis, glutamate-1-semialdehyde aminomutase (GSAM). The inhibition effect is caused by an enzymatic deprotonation of the neurotoxin and requires the aldimine (PLP) form of the cofactor at the active site. In this study, we show that a single-point mutation confers resistance to gabaculine. A combined functional and structural analysis of wild-type GSAM in complex with gabaculine and the GSAM(M248I) form allowed us to decipher in atomic detail the molecular basis of this unique resistance. Interestingly, the gabaculine tolerance is caused by the absence of an essential water molecule that has a dual functional role. It serves as a nucleophilic shuttle for the hydroxyl anion along the reaction pathway and holds active-site Lys273 in a catalytically competent conformation. The single-point mutant is not able to fix this catalytic water between the beta-branched side chain of Ile248 and Lys273. As a consequence, the mutant enzyme is trapped in a gabaculine-insensitive but still enzymatically active amine (PMP) form.

  • Organizational Affiliation

    Department of Chemistry, University of Manitoba, 144 Dysart Rd, Winnipeg, R3T 2N2, Manitoba, Canada.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Glutamate-1-semialdehyde 2,1-aminomutase
A, B
427Synechococcus elongatus PCC 6301Mutation(s): 1 
Gene Names: hemLgsasyc0881_c
Find proteins for P24630 (Synechococcus sp. (strain ATCC 27144 / PCC 6301 / SAUG 1402/1))
Explore P24630 
Go to UniProtKB:  P24630
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP24630
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.35 Å
  • R-Value Free: 0.241 
  • R-Value Work: 0.208 
  • R-Value Observed: 0.208 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 67.938α = 90
b = 107.868β = 90
c = 123.066γ = 90
Software Package:
Software NamePurpose
HKL-2000data collection
MOSFLMdata reduction
SCALAdata scaling

Structure Validation

View Full Validation Report

Ligand Structure Quality Assessment 

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2009-11-24
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance
  • Version 1.2: 2021-10-20
    Changes: Database references
  • Version 1.3: 2023-09-06
    Changes: Data collection, Refinement description