6QWQ

Structure of gtPebB


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.90 Å
  • R-Value Free: 0.233 
  • R-Value Work: 0.211 
  • R-Value Observed: 0.212 

wwPDB Validation   3D Report Full Report


This is version 1.3 of the entry. See complete history


Literature

Crystal structure of the first eukaryotic bilin reductaseGtPEBB reveals a flipped binding mode of dihydrobiliverdin.

Sommerkamp, J.A.Frankenberg-Dinkel, N.Hofmann, E.

(2019) J Biol Chem 294: 13889-13901

  • DOI: https://doi.org/10.1074/jbc.RA119.009306
  • Primary Citation of Related Structures:  
    6QWQ, 6QX6

  • PubMed Abstract: 

    Phycobilins are light-harvesting pigments of cyanobacteria, red algae, and cryptophytes. The biosynthesis of phycoerythrobilin (PEB) is catalyzed by the subsequent action of two ferredoxin-dependent bilin reductases (FDBRs). Although 15,16-dihydrobiliverdin (DHBV):ferredoxin oxidoreductase (PebA) catalyzes the two-electron reduction of biliverdin IXα to 15,16-DHBV, PEB:ferredoxin oxidoreductase (PebB) reduces this intermediate further to PEB. Interestingly, marine viruses encode the FDBR PebS combining both activities within one enzyme. Although PebA and PebS share a canonical fold with similar substrate-binding pockets, the structural determinants for the stereo- and regiospecific modification of their tetrapyrrole substrates are incompletely understood, also because of the lack of a PebB structure. Here, we solved the X-ray crystal structures of both substrate-free and -bound PEBB from the cryptophyte Guillardia theta at 1.90 and 1.65 Å, respectively. The structures of PEBB exhibit the typical α/β/α-sandwich fold. Interestingly, the open-chain tetrapyrrole substrate DHBV is bound in an unexpected flipped orientation within the canonical FDBR active site. Biochemical analyses of the WT enzyme and active site variants identified two central aspartate residues Asp-99 and Asp-219 as essential for catalytic activity. In addition, the conserved Arg-215 plays a critical role in substrate specificity, binding orientation, and active site integrity. Because these critical residues are conserved within certain FDBRs displaying A-ring reduction activity, we propose that they present a conserved mechanism for this reaction. The flipped substrate-binding mode indicates that two-electron reducing FDBRs utilize the same primary site within the binding pocket and that substrate orientation is the determinant for A- or D-ring regiospecificity.


  • Organizational Affiliation

    Protein Crystallography, Faculty of Biology and Biotechnology, Ruhr University Bochum, 44801 Bochum, Germany.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Ferredoxin bilin reductase plastid275Guillardia theta CCMP2712Mutation(s): 0 
Gene Names: GUITHDRAFT_96430
UniProt
Find proteins for L1IWQ9 (Guillardia theta (strain CCMP2712))
Explore L1IWQ9 
Go to UniProtKB:  L1IWQ9
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupL1IWQ9
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.90 Å
  • R-Value Free: 0.233 
  • R-Value Work: 0.211 
  • R-Value Observed: 0.212 
  • Space Group: P 62
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 109.6α = 90
b = 109.6β = 90
c = 47.98γ = 120
Software Package:
Software NamePurpose
PHENIXrefinement
XDSdata reduction
XSCALEdata scaling
PHENIXphasing

Structure Validation

View Full Validation Report



Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
German Research FoundationGermanyHO2600-3

Revision History  (Full details and data files)

  • Version 1.0: 2019-08-07
    Type: Initial release
  • Version 1.1: 2019-08-14
    Changes: Data collection, Database references
  • Version 1.2: 2019-10-02
    Changes: Data collection, Database references
  • Version 1.3: 2024-05-15
    Changes: Data collection, Database references