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Influence of Cupric (Cu2+) Ions on the Iron Oxidation Mechanism by DNA-Binding Protein from Starved Cells (Dps) from Marinobacter nauticus
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Orientador(es)
Resumo(s)
Dps proteins (DNA-binding proteins from starved cells) are multifunctional stress defense proteins from the Ferritin family expressed in Prokarya during starvation and/or acute oxidative stress. Besides shielding bacterial DNA through binding and condensation, Dps proteins protect the cell from reactive oxygen species by oxidizing and storing ferrous ions within their cavity, using either hydrogen peroxide or molecular oxygen as the co-substrate, thus reducing the toxic effects of Fenton reactions. Interestingly, the interaction between Dps and transition metals (other than iron) is a known but relatively uncharacterized phenomenon. The impact of non-iron metals on the structure and function of Dps proteins is a current topic of research. This work focuses on the interaction between the Dps from Marinobacter nauticus (a marine facultative anaerobe bacterium capable of degrading petroleum hydrocarbons) and the cupric ion (Cu2+), one of the transition metals of greater biological relevance. Results obtained using electron paramagnetic resonance (EPR), Mössbauer and UV/Visible spectroscopies revealed that Cu2+ ions bind to specific binding sites in Dps, exerting a rate-enhancing effect on the ferroxidation reaction in the presence of molecular oxygen and directly oxidizing ferrous ions when no other co-substrate is present, in a yet uncharacterized redox reaction. This prompts additional research on the catalytic properties of Dps proteins.
Descrição
Funding Information: This work was financed by national funds from the Fundação para a Ciência e a Tecnologia (FCT-MCTES), I.P., in the scope of the project UIDB/04378/2020 of the Research Unit on Applied Molecular Biosciences–UCIBIO and LA/P/0140/2020 of the Associate Laboratory Institute for Health and Bioeconomy–i4HB; grant PTDC/BIAPRO/111485/2009 (to P.T.) and PTDC/QUI/64248/2006 (to A.S.P). This work was also supported by the Radiation Biology and Biophysics Doctoral Training Program–RaBBiT, financed by FCT-MCTES, grants PD/00193/2012; UIDB/04378/2020 (UCIBIO) and UIDB/00068/2020 (CEFITEC). The RaBBiT Doctoral Training Program awarded fellowships to J.P.L.G. (PD/BD/135476/2017 and COVID/BD/152497/2022) and to D.P. (SFRH/BD/52535/2014). Publisher Copyright: © 2023 by the authors.
Palavras-chave
copper in biology DNA-binding protein from starved cells (Dps) electron paramagnetic resonance spectroscopy (EPR) ferroxidase centers iron homeostasis iron oxidation Mössbauer spectroscopy transition metals in biology Catalysis Molecular Biology Spectroscopy Computer Science Applications Physical and Theoretical Chemistry Organic Chemistry Inorganic Chemistry SDG 14 - Life Below Water