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Arresting the Catalytic Arginine in Chlorite Dismutases: Impact on Heme Coordination, Thermal Stability, and Catalysis
[Image: see text] Chlorite dismutases (Clds) are heme b-containing oxidoreductases that can decompose chlorite to chloride and molecular oxygen. They are divided in two clades that differ in oligomerization, subunit architecture, and the hydrogen-bonding network of the distal catalytic arginine, whi...
Autores principales: | , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
American
Chemical Society
2021
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7931450/ https://www.ncbi.nlm.nih.gov/pubmed/33586945 http://dx.doi.org/10.1021/acs.biochem.0c00910 |
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author | Schmidt, Daniel Serra, Ilenia Mlynek, Georg Pfanzagl, Vera Hofbauer, Stefan Furtmüller, Paul G. Djinović-Carugo, Kristina Van Doorslaer, Sabine Obinger, Christian |
author_facet | Schmidt, Daniel Serra, Ilenia Mlynek, Georg Pfanzagl, Vera Hofbauer, Stefan Furtmüller, Paul G. Djinović-Carugo, Kristina Van Doorslaer, Sabine Obinger, Christian |
author_sort | Schmidt, Daniel |
collection | PubMed |
description | [Image: see text] Chlorite dismutases (Clds) are heme b-containing oxidoreductases that can decompose chlorite to chloride and molecular oxygen. They are divided in two clades that differ in oligomerization, subunit architecture, and the hydrogen-bonding network of the distal catalytic arginine, which is proposed to switch between two conformations during turnover. To understand the impact of the conformational dynamics of this basic amino acid on heme coordination, structure, and catalysis, Cld from Cyanothece sp. PCC7425 was used as a model enzyme. As typical for a clade 2 Cld, its distal arginine 127 is hydrogen-bonded to glutamine 74. The latter has been exchanged with either glutamate (Q74E) to arrest R127 in a salt bridge or valine (Q74V) that mirrors the setting in clade 1 Clds. We present the X-ray crystal structures of Q74V and Q74E and demonstrate the pH-induced changes in the environment and coordination of the heme iron by ultraviolet–visible, circular dichroism, and electron paramagnetic resonance spectroscopies as well as differential scanning calorimetry. The conformational dynamics of R127 is shown to have a significant role in heme coordination during the alkaline transition and in the thermal stability of the heme cavity, whereas its impact on the catalytic efficiency of chlorite degradation is relatively small. The findings are discussed with respect to (i) the flexible loop connecting the N-terminal and C-terminal ferredoxin-like domains, which differs in clade 1 and clade 2 Clds and carries Q74 in clade 2 proteins, and (ii) the proposed role(s) of the arginine in catalysis. |
format | Online Article Text |
id | pubmed-7931450 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2021 |
publisher | American
Chemical Society |
record_format | MEDLINE/PubMed |
spelling | pubmed-79314502021-03-04 Arresting the Catalytic Arginine in Chlorite Dismutases: Impact on Heme Coordination, Thermal Stability, and Catalysis Schmidt, Daniel Serra, Ilenia Mlynek, Georg Pfanzagl, Vera Hofbauer, Stefan Furtmüller, Paul G. Djinović-Carugo, Kristina Van Doorslaer, Sabine Obinger, Christian Biochemistry [Image: see text] Chlorite dismutases (Clds) are heme b-containing oxidoreductases that can decompose chlorite to chloride and molecular oxygen. They are divided in two clades that differ in oligomerization, subunit architecture, and the hydrogen-bonding network of the distal catalytic arginine, which is proposed to switch between two conformations during turnover. To understand the impact of the conformational dynamics of this basic amino acid on heme coordination, structure, and catalysis, Cld from Cyanothece sp. PCC7425 was used as a model enzyme. As typical for a clade 2 Cld, its distal arginine 127 is hydrogen-bonded to glutamine 74. The latter has been exchanged with either glutamate (Q74E) to arrest R127 in a salt bridge or valine (Q74V) that mirrors the setting in clade 1 Clds. We present the X-ray crystal structures of Q74V and Q74E and demonstrate the pH-induced changes in the environment and coordination of the heme iron by ultraviolet–visible, circular dichroism, and electron paramagnetic resonance spectroscopies as well as differential scanning calorimetry. The conformational dynamics of R127 is shown to have a significant role in heme coordination during the alkaline transition and in the thermal stability of the heme cavity, whereas its impact on the catalytic efficiency of chlorite degradation is relatively small. The findings are discussed with respect to (i) the flexible loop connecting the N-terminal and C-terminal ferredoxin-like domains, which differs in clade 1 and clade 2 Clds and carries Q74 in clade 2 proteins, and (ii) the proposed role(s) of the arginine in catalysis. American Chemical Society 2021-02-15 2021-03-02 /pmc/articles/PMC7931450/ /pubmed/33586945 http://dx.doi.org/10.1021/acs.biochem.0c00910 Text en © 2021 The Authors. Published by American Chemical Society This is an open access article published under an ACS AuthorChoice License (https://creativecommons.org/licenses/by/4.0/) , which permits copying and redistribution of the article or any adaptations for non-commercial purposes. |
spellingShingle | Schmidt, Daniel Serra, Ilenia Mlynek, Georg Pfanzagl, Vera Hofbauer, Stefan Furtmüller, Paul G. Djinović-Carugo, Kristina Van Doorslaer, Sabine Obinger, Christian Arresting the Catalytic Arginine in Chlorite Dismutases: Impact on Heme Coordination, Thermal Stability, and Catalysis |
title | Arresting the Catalytic Arginine in Chlorite Dismutases:
Impact on Heme Coordination, Thermal Stability, and Catalysis |
title_full | Arresting the Catalytic Arginine in Chlorite Dismutases:
Impact on Heme Coordination, Thermal Stability, and Catalysis |
title_fullStr | Arresting the Catalytic Arginine in Chlorite Dismutases:
Impact on Heme Coordination, Thermal Stability, and Catalysis |
title_full_unstemmed | Arresting the Catalytic Arginine in Chlorite Dismutases:
Impact on Heme Coordination, Thermal Stability, and Catalysis |
title_short | Arresting the Catalytic Arginine in Chlorite Dismutases:
Impact on Heme Coordination, Thermal Stability, and Catalysis |
title_sort | arresting the catalytic arginine in chlorite dismutases:
impact on heme coordination, thermal stability, and catalysis |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7931450/ https://www.ncbi.nlm.nih.gov/pubmed/33586945 http://dx.doi.org/10.1021/acs.biochem.0c00910 |
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