Crystal Structure of Chlorite Dismutase, a Detoxifying Enzyme Producing Molecular Oxygen

de Geus, Daniël C. and Thomassen, Ellen A. J. and Hagedoorn, Peter-Leon and Pannu, Navraj S. and van Duijn, Esther and Abrahams, Jan Pieter. (2009) Crystal Structure of Chlorite Dismutase, a Detoxifying Enzyme Producing Molecular Oxygen. Journal of Molecular Biology, 387 (1). pp. 192-206.

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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 angstrom 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.
Faculties and Departments:05 Faculty of Science > Departement Biozentrum > Structural Biology & Biophysics > Nano-diffraction of Biological Specimen (Abrahams)
UniBasel Contributors:Abrahams, Jan Pieter
Item Type:Article, refereed
Article Subtype:Research Article
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:06 Nov 2020 08:17
Deposited On:06 Nov 2020 08:17

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