Experimental Data Snapshot

  • Resolution: 2.00 Å
  • R-Value Free: 0.252 
  • R-Value Work: 0.215 
  • R-Value Observed: 0.218 

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Crystal structure of 3-amino-5-hydroxybenzoic acid (AHBA) synthase.

Eads, J.C.Beeby, M.Scapin, G.Yu, T.W.Floss, H.G.

(1999) Biochemistry 38: 9840-9849

  • DOI: https://doi.org/10.1021/bi990018q
  • Primary Citation of Related Structures:  
    1B9H, 1B9I

  • PubMed Abstract: 

    The biosynthesis of ansamycin antibiotics, including rifamycin B, involves the synthesis of an aromatic precursor, 3-amino-5-hydroxybenzoic acid (AHBA), which serves as starter for the assembly of the antibiotics' polyketide backbone. The terminal enzyme of AHBA formation, AHBA synthase, is a dimeric, pyridoxal 5'-phosphate (PLP) dependent enzyme with pronounced sequence homology to a number of PLP enzymes involved in the biosynthesis of antibiotic sugar moieties. The structure of AHBA synthase from Amycolatopsis mediterranei has been determined to 2.0 A resolution, with bound cofactor, PLP, and in a complex with PLP and an inhibitor (gabaculine). The overall fold of AHBA synthase is similar to that of the aspartate aminotransferase family of PLP-dependent enzymes, with a large domain containing a seven-stranded beta-sheet surrounded by alpha-helices and a smaller domain consisting of a four-stranded antiparallel beta-sheet and four alpha-helices. The uninhibited form of the enzyme shows the cofactor covalently linked to Lys188 in an internal aldimine linkage. On binding the inhibitor, gabaculine, the internal aldimine linkage is broken, and a covalent bond is observed between the cofactor and inhibitor. The active site is composed of residues from two subunits of AHBA synthase, indicating that AHBA synthase is active as a dimer.

  • Organizational Affiliation

    School of Biochemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT, U.K.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
PROTEIN (3-AMINO-5-HYDROXYBENZOIC ACID SYNTHASE)388Amycolatopsis mediterraneiMutation(s): 0 
Find proteins for O52552 (Amycolatopsis mediterranei (strain S699))
Explore O52552 
Go to UniProtKB:  O52552
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupO52552
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on PLP

Download Ideal Coordinates CCD File 
C8 H10 N O6 P
Experimental Data & Validation

Experimental Data

  • Resolution: 2.00 Å
  • R-Value Free: 0.252 
  • R-Value Work: 0.215 
  • R-Value Observed: 0.218 
  • Space Group: P 32 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 89.7α = 90
b = 89.7β = 90
c = 127.7γ = 120
Software Package:
Software NamePurpose

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 1999-08-13
    Type: Initial release
  • Version 1.1: 2008-04-26
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Derived calculations, Version format compliance
  • Version 1.3: 2023-12-27
    Changes: Data collection, Database references, Derived calculations