2VXH

The crystal structure of chlorite dismutase: a detox enzyme producing molecular oxygen

Summary for 2VXH

• Entry DOI: 10.2210/pdb2vxh/pdb
• Descriptor: CHLORITE DISMUTASE, PROTOPORPHYRIN IX CONTAINING FE, THIOCYANATE ION, ... (5 entities in total)
• Functional Keywords: heme-based enzyme, oxidoreductase, chlorate respiration, molecular oxygen production
• Biological source: AZOSPIRA ORYZAE
• Total number of polymer chains: 6
• Total formula weight: 175297.54

Authors

De Geus, D.C.,Thomassen, E.A.J.,Hagedoorn, P.L.,Pannu, N.S.,Abrahams, J.P. (deposition date: 2008-07-04, release date: 2009-03-03, Last modification date: 2024-05-08)

Primary citation

De Geus, D.C.,Thomassen, E.A.J.,Hagedoorn, P.L.,Pannu, N.S.,Van Duijn, E.,Abrahams, J.P.
Crystal Structure of Chlorite Dismutase, a Detoxifying Enzyme Producing Molecular Oxygen
J.Mol.Biol., 387:192-, 2009

PubMed Abstract: Chlorite dismutase (Cld) is a key enzyme of perchlorate and chlorate respiration. This heme-based protein reduces the toxic compound chlorite into the innocuous chloride anion in a very efficient way while producing molecular oxygen. A sequence comparison between Cld homologues shows a highly conserved family. The crystal structure of Azospira oryzae strain GR-1 Cld is reported to 2.1 A resolution. The structure reveals a hexameric organization of the Cld, while each monomer exhibits a ferredoxin-like fold. The six subunits are organized in a ring structure with a maximal diameter of 9 nm and an inner diameter of 2 nm. The heme active-site pocket is solvent accessible both from the inside and the outside of the ring. Moreover, a second anion binding site that could accommodate the assumed reaction intermediate ClO(-) for further transformation has been identified near the active site. The environment of the heme cofactor was investigated with electron paramagnetic resonance spectroscopy. Apart from the high-spin ferric signal of the five-coordinate resting-state enzyme, two low-spin signals were found corresponding to six-coordinate species. The current crystal structure confirms and complements a recently proposed catalytic mechanism that proceeds via a ferryl species and a ClO(-) anion. Our structural data exclude cooperativity between the iron centers.

PubMed: 19361444
DOI: 10.1016/J.JMB.2009.01.036

Experimental method

X-RAY DIFFRACTION (2.1 Å)