3IHG

Crystal structure of a ternary complex of aklavinone-11 hydroxylase with FAD and aklavinone


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.49 Å
  • R-Value Free: 0.255 
  • R-Value Work: 0.204 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Structural basis for substrate recognition and specificity in aklavinone-11-hydroxylase from rhodomycin biosynthesis.

Lindqvist, Y.Koskiniemi, H.Jansson, A.Sandalova, T.Schnell, R.Liu, Z.Mantsala, P.Niemi, J.Schneider, G.

(2009) J.Mol.Biol. 393: 966-977

  • DOI: 10.1016/j.jmb.2009.09.003

  • PubMed Abstract: 
  • In the biosynthesis of several anthracyclines, aromatic polyketides produced by many Streptomyces species, the aglycone core is modified by a specific flavin adenine dinucleotide (FAD)- and NAD(P)H-dependent aklavinone-11-hydroxylase. Here, we report ...

    In the biosynthesis of several anthracyclines, aromatic polyketides produced by many Streptomyces species, the aglycone core is modified by a specific flavin adenine dinucleotide (FAD)- and NAD(P)H-dependent aklavinone-11-hydroxylase. Here, we report the crystal structure of a ternary complex of this enzyme from Streptomyces purpurascens, RdmE, with FAD and the substrate aklavinone. The enzyme is built up of three domains, a FAD-binding domain, a domain involved in substrate binding, and a C-terminal thioredoxin-like domain of unknown function. RdmE exhibits structural similarity to aromatic hydroxylases from the p-hydroxybenzoate hydroxylase family, but unlike most other related enzymes, RdmE is a monomer. The substrate is bound in a hydrophobic pocket in the interior of the enzyme, and access to this pocket is provided through a different route than for the isoalloxazine ring of FAD-the backside of the ligand binding cleft. The architecture of the substrate binding pocket and the observed enzyme-aklavinone interactions provide a structural explanation for the specificity of the enzyme for non-glycosylated substrates with C9-R stereochemistry. The isoalloxazine ring of the flavin cofactor is bound in the "out" conformation but can be modeled in the "in" conformation without invoking large conformational changes of the enzyme. This model places the flavin ring in a position suitable for catalysis, almost perpendicular to the tetracyclic ring system of the substrate and with a distance of the C4a carbon atom of the isoalloxazine ring to the C-11 carbon atom of the substrate of 4.8 A. The structure suggested that a Tyr224-Arg373 pair might be involved in proton abstraction at the C-6 hydroxyl group, thereby increasing the nucleophilicity of the aromatic ring system and facilitating electrophilic attack by the perhydroxy-flavin intermediate. Replacement of Tyr224 by phenylalanine results in inactive enzyme, whereas mutants at position Arg373 retain catalytic activity close to wild-type level. These data establish an essential role of residue Tyr224 in catalysis, possibly in aligning the substrate in a position suitable for catalysis.


    Organizational Affiliation

    Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm S-171 77, Sweden.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
RdmE
A, B, C
535Streptomyces purpurascensMutation(s): 0 
Gene Names: rdmE
EC: 1.14.13.180
Find proteins for Q54530 (Streptomyces purpurascens)
Go to UniProtKB:  Q54530
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
SO4
Query on SO4

Download SDF File 
Download CCD File 
A, B, C
SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L
 Ligand Interaction
FAD
Query on FAD

Download SDF File 
Download CCD File 
A, B, C
FLAVIN-ADENINE DINUCLEOTIDE
C27 H33 N9 O15 P2
VWWQXMAJTJZDQX-UYBVJOGSSA-N
 Ligand Interaction
VAK
Query on VAK

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Download CCD File 
A, B, C
methyl (1R,2R,4S)-2-ethyl-2,4,5,7-tetrahydroxy-6,11-dioxo-1,2,3,4,6,11-hexahydrotetracene-1-carboxylate
Aklavinone
C22 H20 O8
RACGRCLGVYXIAO-YOKWENHESA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.49 Å
  • R-Value Free: 0.255 
  • R-Value Work: 0.204 
  • Space Group: P 63
Unit Cell:
Length (Å)Angle (°)
a = 183.035α = 90.00
b = 183.035β = 90.00
c = 99.639γ = 120.00
Software Package:
Software NamePurpose
REFMACrefinement
PHASERphasing
SCALAdata scaling
MOSFLMdata reduction
MAR345dtbdata collection

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2009-09-29
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Version format compliance
  • Version 1.2: 2018-03-07
    Type: Data collection