4XIW

Carbonic anhydrase Cah3 from Chlamydomonas reinhardtii in complex with acetazolamide


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.6 Å
  • R-Value Free: 0.226 
  • R-Value Work: 0.161 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Crystal Structure and Functional Characterization of Photosystem II-Associated Carbonic Anhydrase CAH3 in Chlamydomonas reinhardtii.

Benlloch, R.Shevela, D.Hainzl, T.Grundstrom, C.Shutova, T.Messinger, J.Samuelsson, G.Sauer-Eriksson, A.E.

(2015) Plant Physiol. 167: 950-962

  • DOI: 10.1104/pp.114.253591
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • In oxygenic photosynthesis, light energy is stored in the form of chemical energy by converting CO2 and water into carbohydrates. The light-driven oxidation of water that provides the electrons and protons for the subsequent CO2 fixation takes place ...

    In oxygenic photosynthesis, light energy is stored in the form of chemical energy by converting CO2 and water into carbohydrates. The light-driven oxidation of water that provides the electrons and protons for the subsequent CO2 fixation takes place in photosystem II (PSII). Recent studies show that in higher plants, HCO3 (-) increases PSII activity by acting as a mobile acceptor of the protons produced by PSII. In the green alga Chlamydomonas reinhardtii, a luminal carbonic anhydrase, CrCAH3, was suggested to improve proton removal from PSII, possibly by rapid reformation of HCO3 (-) from CO2. In this study, we investigated the interplay between PSII and CrCAH3 by membrane inlet mass spectrometry and x-ray crystallography. Membrane inlet mass spectrometry measurements showed that CrCAH3 was most active at the slightly acidic pH values prevalent in the thylakoid lumen under illumination. Two crystal structures of CrCAH3 in complex with either acetazolamide or phosphate ions were determined at 2.6- and 2.7-Å resolution, respectively. CrCAH3 is a dimer at pH 4.1 that is stabilized by swapping of the N-terminal arms, a feature not previously observed in α-type carbonic anhydrases. The structure contains a disulfide bond, and redox titration of CrCAH3 function with dithiothreitol suggested a possible redox regulation of the enzyme. The stimulating effect of CrCAH3 and CO2/HCO3 (-) on PSII activity was demonstrated by comparing the flash-induced oxygen evolution pattern of wild-type and CrCAH3-less PSII preparations. We showed that CrCAH3 has unique structural features that allow this enzyme to maximize PSII activity at low pH and CO2 concentration.


    Organizational Affiliation

    Department of Forest Genetics and Plant Physiology (R.B) and Department of Plant Physiology (T.S., G.S.), Umeå Plant Science Centre, and Department of Chemistry, Chemistry Biology Centre (D.S., T.H., C.G., J.M., A.E.S.-E.), Umeå University, SE-90187 Umea, Sweden.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Carbonic anhydrase, alpha type
A, B, C, D, E, F, G, H
239Chlamydomonas reinhardtiiMutation(s): 0 
Gene Names: CAH3
Find proteins for Q39588 (Chlamydomonas reinhardtii)
Go to UniProtKB:  Q39588
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
ZN
Query on ZN

Download SDF File 
Download CCD File 
A, B, C, D, E, F, G, H
ZINC ION
Zn
PTFCDOFLOPIGGS-UHFFFAOYSA-N
 Ligand Interaction
2HP
Query on 2HP

Download SDF File 
Download CCD File 
A, B, C, D, E, F, G, H
DIHYDROGENPHOSPHATE ION
H2 O4 P
NBIIXXVUZAFLBC-UHFFFAOYSA-M
 Ligand Interaction
AZM
Query on AZM

Download SDF File 
Download CCD File 
A, B, C, D, E, F, G, H
5-ACETAMIDO-1,3,4-THIADIAZOLE-2-SULFONAMIDE
C4 H6 N4 O3 S2
BZKPWHYZMXOIDC-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.6 Å
  • R-Value Free: 0.226 
  • R-Value Work: 0.161 
  • Space Group: P 32 2 1
Unit Cell:
Length (Å)Angle (°)
a = 139.356α = 90.00
b = 139.356β = 90.00
c = 203.209γ = 120.00
Software Package:
Software NamePurpose
PHENIXrefinement
SCALAdata scaling
PHASERphasing
XDSdata reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
Swedish Research CouncilSweden--

Revision History 

  • Version 1.0: 2015-02-11
    Type: Initial release
  • Version 1.1: 2015-03-11
    Type: Database references