Impact of the dynamics of the catalytic arginine on nitrite and chlorite binding by dimeric chlorite dismutase

Serra, I. ; Schmidt, D. ; Pfanzagl, V. ; Mlynek, G. ; Hofbauer, S. ; Djinovic-Carugo, K. ; Furtmüller, P. G. ; García-Rubio, Inés (Universidad de Zaragoza) ; Van Doorslaer, S. ; Obinger, C.

Resumen: Chlorite dismutases (Clds) are heme b containing oxidoreductases able to decompose chlorite to chloride and molecular oxygen. This work analyses the impact of the distal, flexible and catalytic arginine on the binding of anionic angulate ligands like nitrite and the substrate chlorite. Dimeric Cld from Cyanothece sp. PCC7425 was used as a model enzyme. We have investigated wild-type CCld having the distal catalytic R127 hydrogen-bonded to glutamine Q74 and variants with R127 (i) being arrested in a salt-bridge with a glutamate (Q74E), (ii) being fully flexible (Q74V) or (iii) substituted by either alanine (R127A) or lysine (R127K). We present the electronic and spectral signatures of the high-spin ferric proteins and the corresponding low-spin nitrite complexes elucidated by UV–visible, circular dichroism and electron paramagnetic resonance spectroscopies. Furthermore, we demonstrate the impact of the dynamics of R127 on the thermal stability of the respective nitrite adducts and present the X-ray crystal structures of the nitrite complexes of wild-type CCld and the variants Q74V, Q74E and R127A. In addition, the molecular dynamics (MD) and the binding modi of nitrite and chlorite to the ferric wild-type enzyme and the mutant proteins and the interaction of the oxoanions with R127 have been analysed by MD simulations. The findings are discussed with respect to the role(s) of R127 in ligand and chlorite binding and substrate degradation.

Idioma: Inglés

DOI: 10.1016/j.jinorgbio.2021.111689

Año: 2022

Publicado en: Journal of Inorganic Biochemistry 227 (2022), 111689 [15 pp.]
ISSN: 0162-0134

Factor impacto JCR: 3.9 (2022)

Categ. JCR: CHEMISTRY, INORGANIC & NUCLEAR rank: 8 / 42 = 0.19 (2022) - Q1 - T1
Categ. JCR: BIOCHEMISTRY & MOLECULAR BIOLOGY rank: 126 / 285 = 0.442 (2022) - Q2 - T2

Factor impacto CITESCORE: 7.0 - Chemistry (Q1) - Biochemistry, Genetics and Molecular Biology (Q2)

Factor impacto SCIMAGO: 0.646 - Inorganic Chemistry (Q1) - Biochemistry (Q2)

Financiación: info:eu-repo/grantAgreement/EC/H2020/813209/EU/Paramagnetic Species in Catalysis Research. A Unified Approach Towards Heterogeneous, Homogeneous and Enzyme Catalysis/PARACAT

Tipo y forma: Artículo (PostPrint)

Área (Departamento): Área Física Materia Condensada (Dpto. Física Materia Condensa.)