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Article

Atomic Force Microscopy to Elicit Conformational Transitions of Ferredoxin-Dependent Flavin Thioredoxin Reductases

1
Instituto de Nanociencia y Materiales de Aragón (INMA), CSIC-Universidad de Zaragoza, 50009 Zaragoza, Spain
2
Laboratorio de Microscopías Avanzadas (LMA), Universidad de Zaragoza, 50018 Zaragoza, Spain
3
Department of Abiotic Stress, Instituto de Recursos Naturales y Agrobiología de Salamanca (IRNASA-CSIC), 37008 Salamanca, Spain
4
Departamento de Bioquímica y Biología Molecular y Celular, Facultad de Ciencias, Instituto de Biocomputación y Física de Sistemas Complejos (GBsC-CSIC Joint Unit), Universidad de Zaragoza, 50018 Zaragoza, Spain
5
Fundación ARAID, 50018 Zaragoza, Spain
*
Authors to whom correspondence should be addressed.
Academic Editors: Luis M. Mateos and Michal Letek
Antioxidants 2021, 10(9), 1437; https://doi.org/10.3390/antiox10091437
Received: 28 July 2021 / Revised: 2 September 2021 / Accepted: 6 September 2021 / Published: 9 September 2021
(This article belongs to the Special Issue Redox Biology in Microorganisms)
Flavin and redox-active disulfide domains of ferredoxin-dependent flavin thioredoxin reductase (FFTR) homodimers should pivot between flavin-oxidizing (FO) and flavin-reducing (FR) conformations during catalysis, but only FR conformations have been detected by X-ray diffraction and scattering techniques. Atomic force microscopy (AFM) is a single-molecule technique that allows the observation of individual biomolecules with sub-nm resolution in near-native conditions in real-time, providing sampling of molecular properties distributions and identification of existing subpopulations. Here, we show that AFM is suitable to evaluate FR and FO conformations. In agreement with imaging under oxidizing condition, only FR conformations are observed for Gloeobacter violaceus FFTR (GvFFTR) and isoform 2 of Clostridium acetobutylicum FFTR (CaFFTR2). Nonetheless, different relative dispositions of the redox-active disulfide and FAD-binding domains are detected for FR homodimers, indicating a dynamic disposition of disulfide domains regarding the central protein core in solution. This study also shows that AFM can detect morphological changes upon the interaction of FFTRs with their protein partners. In conclusion, this study paves way for using AFM to provide complementary insight into the FFTR catalytic cycle at pseudo-physiological conditions. However, future approaches for imaging of FO conformations will require technical developments with the capability of maintaining the FAD-reduced state within the protein during AFM scanning. View Full-Text
Keywords: thioredoxin reductase; atomic force microscopy; protein interactions; redox-active disulfide; single-molecule methods; homodimers; flavoproteins thioredoxin reductase; atomic force microscopy; protein interactions; redox-active disulfide; single-molecule methods; homodimers; flavoproteins
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MDPI and ACS Style

Marcuello, C.; Frempong, G.A.; Balsera, M.; Medina, M.; Lostao, A. Atomic Force Microscopy to Elicit Conformational Transitions of Ferredoxin-Dependent Flavin Thioredoxin Reductases. Antioxidants 2021, 10, 1437. https://doi.org/10.3390/antiox10091437

AMA Style

Marcuello C, Frempong GA, Balsera M, Medina M, Lostao A. Atomic Force Microscopy to Elicit Conformational Transitions of Ferredoxin-Dependent Flavin Thioredoxin Reductases. Antioxidants. 2021; 10(9):1437. https://doi.org/10.3390/antiox10091437

Chicago/Turabian Style

Marcuello, Carlos, Gifty A. Frempong, Mónica Balsera, Milagros Medina, and Anabel Lostao. 2021. "Atomic Force Microscopy to Elicit Conformational Transitions of Ferredoxin-Dependent Flavin Thioredoxin Reductases" Antioxidants 10, no. 9: 1437. https://doi.org/10.3390/antiox10091437

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