5K90

Crystal structure of dimeric chlorite dismutase from Cyanothece sp. PCC7425 in complex with isothiocyanate

Summary for 5K90

• Entry DOI: 10.2210/pdb5k90/pdb
• Descriptor: Chlorite dismutase, isothiocyanate, PROTOPORPHYRIN IX CONTAINING FE, ... (7 entities in total)
• Functional Keywords: chlorite dismutase, cyanobacteria, heme, ferredoxin-like fold, oxidoreductase
• Biological source: Cyanothece sp. (strain PCC 7425 / ATCC 29141)
• Total number of polymer chains: 4
• Total formula weight: 91071.11

Authors

Puehringer, D.,Schaffner, I.,Mlynek, G.,Obinger, C.,Djinovic-Carugo, K. (deposition date: 2016-05-31, release date: 2017-06-21, Last modification date: 2024-05-08)

Primary citation

Schaffner, I.,Mlynek, G.,Flego, N.,Puhringer, D.,Libiseller-Egger, J.,Coates, L.,Hofbauer, S.,Bellei, M.,Furtmuller, P.G.,Battistuzzi, G.,Smulevich, G.,Djinovic-Carugo, K.,Obinger, C.
Molecular Mechanism of Enzymatic Chlorite Detoxification: Insights from Structural and Kinetic Studies.
ACS Catal, 7:7962-7976, 2017

PubMed Abstract: The heme enzyme chlorite dismutase (Cld) catalyzes the degradation of chlorite to chloride and dioxygen. Although structure and steady-state kinetics of Clds have been elucidated, many questions remain (e.g., the mechanism of chlorite cleavage and the pH dependence of the reaction). Here, we present high-resolution X-ray crystal structures of a dimeric Cld at pH 6.5 and 8.5, its fluoride and isothiocyanate complexes and the neutron structure at pH 9.0 together with the pH dependence of the Fe(III)/Fe(II) couple, and the UV-vis and resonance Raman spectral features. We demonstrate that the distal Arg127 cannot act as proton acceptor and is fully ionized even at pH 9.0 ruling out its proposed role in dictating the pH dependence of chlorite degradation. Stopped-flow studies show that (i) Compound I and hypochlorite do not recombine and (ii) Compound II is the immediately formed redox intermediate that dominates during turnover. Homolytic cleavage of chlorite is proposed.

PubMed: 29142780
DOI: 10.1021/acscatal.7b01749

Experimental method

X-RAY DIFFRACTION (1.28 Å)