Crystal structure of the cyanobacterial plasma membrane Rieske protein PetC3 from Synechocystis PCC 6803

Experimental Data Snapshot

  • Resolution: 1.70 Å
  • R-Value Free: 0.216 
  • R-Value Work: 0.185 
  • R-Value Observed: 0.185 

Starting Model: experimental
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Structural and functional characterisation of the cyanobacterial PetC3 Rieske protein family.

Veit, S.Takeda, K.Tsunoyama, Y.Baymann, F.Nevo, R.Reich, Z.Rogner, M.Miki, K.Rexroth, S.

(2016) Biochim Biophys Acta 1857: 1879-1891

  • DOI: https://doi.org/10.1016/j.bbabio.2016.09.007
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    The cyanobacterium Synechocystis PCC 6803 possesses three Rieske isoforms: PetC1, PetC2 and PetC3. While PetC1 and PetC2 have been identified as alternative subunits of the cytochrome b 6 f complex (b 6 f), PetC3 was localized exclusively within the plasma membrane. The spatial separation of PetC3 from the photosynthetic and respiratory protein complexes raises doubt in its involvement in bioenergetic electron transfer. Here we report a detailed structural and functional characterization of the cyanobacterial PetC3 protein family indicating that PetC3 is not a component of the b 6 f and the photosynthetic electron transport as implied by gene annotation. Instead PetC3 has a distinct function in cell envelope homeostasis. Especially proteomic analysis shows that deletion of petC3 in Synechocystis PCC 6803 primarily affects cell envelope proteins including many nutrient transport systems. Therefore, the observed downregulation in the photosynthetic electron transport - mainly caused by photosystem 2 inactivation - might constitute a stress adaptation. Comprehensive in silico sequence analyses revealed that PetC3 proteins are periplasmic lipoproteins tethered to the plasma membrane with a subclass consisting of soluble periplasmic proteins, i.e. their N-terminal domain is inconsistent with their integration into the b 6 f. For the first time, the structure of PetC3 was determined by X-ray crystallography at an atomic resolution revealing significant high similarities to non-b 6 f Rieske subunits in contrast to PetC1. These results suggest that PetC3 affects processes in the periplasmic compartment that only indirectly influence photosynthetic electron transport. For this reason, we suggest to rename "Photosynthetic electron transport Chain 3" (PetC3) proteins as "periplasmic Rieske proteins" (Prp).

  • Organizational Affiliation

    Plant Biochemistry, Faculty of Biology & Biotechnology, Ruhr University of Bochum, 44780 Bochum, Germany.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Cytochrome b6/f complex iron-sulfur subunit
A, B, C, D
110Synechocystis sp. PCC 6803 substr. KazusaMutation(s): 0 
Gene Names: petC
Find proteins for P74174 (Synechocystis sp. (strain PCC 6803 / Kazusa))
Explore P74174 
Go to UniProtKB:  P74174
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP74174
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 3 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on FES

Download Ideal Coordinates CCD File 
E [auth A],
H [auth B],
I [auth C],
L [auth D]
Fe2 S2
Query on SO4

Download Ideal Coordinates CCD File 
O4 S
Query on NI

Download Ideal Coordinates CCD File 
F [auth A],
G [auth A],
J [auth C],
K [auth C]
Experimental Data & Validation

Experimental Data

  • Resolution: 1.70 Å
  • R-Value Free: 0.216 
  • R-Value Work: 0.185 
  • R-Value Observed: 0.185 
  • Space Group: P 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 21.747α = 80.44
b = 55.011β = 89.87
c = 80.709γ = 84.11
Software Package:
Software NamePurpose
HKL-2000data reduction
SCALEPACKdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2016-08-03
    Type: Initial release
  • Version 1.1: 2016-10-05
    Changes: Database references
  • Version 1.2: 2017-02-22
    Changes: Database references
  • Version 1.3: 2020-02-19
    Changes: Data collection
  • Version 1.4: 2023-11-08
    Changes: Data collection, Database references, Derived calculations, Refinement description