Characterization of the key membrane protein cytochrome Cyc2 from Ghiorsea bivora
- 1Aix Marseille University, Université de Toulon, CNRS, IRD, MIO, Marseille, France.
- 2Aix Marseille University, CNRS, LISM, Marseille, France.
- 3Aix Marseille University, CNRS, BIP, Marseille, France.
Abstract
This study reports the heterologous production, purification, and characterization of the cytochrome Cyc2 TAG1 cluster 1 (Cyc2 TAG1_1 ) from Ghiorsea bivora TAG1 in the outer membrane of Escherichia coli BL21. Using a specific gene construct we optimized solubilization and purification protocols to obtain high‐purity enzyme. This enabled biophysical characterization by EPR, measurement of its midpoint redox potential, and the development of an iron‐oxidizing assay with 2,6‐dichlorophenolindophenol (DCPIP) as an artificial final electron acceptor. The study provides the first quantitative kinetic characterization of a Cyc2 homolog in vitro . The absence of comparable apparent K m or V max values with a natural or artificial electron acceptor in the literature underscores the novelty of our findings. Cyc2 TAG1_1 exhibited an apparent K m of 627 ± 226 μ m for iron sulfate, consistent with iron‐rich hydrothermal vent environments where G. bivora thrives, and an apparent V max of 19 ± 5 μ m ·s −1 . Despite using an artificial electron acceptor that does not accurately represent the natural partner or the real energetic system, the enzyme exhibits apparent kinetic parameters that retain biological significance, with a catalytic efficiency within the range expected for functional electron transfer enzymes. Cyc2 TAG1_1 exhibited a redox potential of −130 ± 20 mV vs SHE which is the lowest reported for Cyc2 homologs. The EPR spectrum is consistent with a low‐spin ferric heme with two axial ligands within the protein barrel. These findings provide the first biochemical characterization of Cyc2 TAG1_1 and support its proposed role in iron oxidation.
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BibTeX
@article{azizi2026characterization,
title = {{Characterization of the key membrane protein cytochrome Cyc2 from Ghiorsea bivora}},
author = {Josiane Azizi and Alain Dolla and Frauke Baymann and Celine Rommevaux and Latifa Elantak and Helene Gaussier and Matthieu Nouailler},
journal = {FEBS Open Bio},
year = {2026},
month = oct,
doi = {10.1002/2211-5463.70350},
url = {https://hal.science/hal-05837036v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Characterization of the key membrane protein cytochrome Cyc2 from Ghiorsea bivora
AU - Josiane Azizi
AU - Alain Dolla
AU - Frauke Baymann
AU - Celine Rommevaux
AU - Latifa Elantak
AU - Helene Gaussier
AU - Matthieu Nouailler
PY - 2026
DA - 2026/10/23
JO - FEBS Open Bio
DO - 10.1002/2211-5463.70350
UR - https://hal.science/hal-05837036v1
AB - This study reports the heterologous production, purification, and characterization of the cytochrome Cyc2 TAG1 cluster 1 (Cyc2 TAG1_1 ) from Ghiorsea bivora TAG1 in the outer membrane of Escherichia coli BL21. Using a specific gene construct we optimized solubilization and purification protocols to obtain high‐purity enzyme. This enabled biophysical characterization by EPR, measurement of its midpoint redox potential, and the development of an iron‐oxidizing assay with 2,6‐dichlorophenolindophenol (DCPIP) as an artificial final electron acceptor. The study provides the first quantitative kinetic characterization of a Cyc2 homolog in vitro . The absence of comparable apparent K m or V max values with a natural or artificial electron acceptor in the literature underscores the novelty of our findings. Cyc2 TAG1_1 exhibited an apparent K m of 627 ± 226 μ m for iron sulfate, consistent with iron‐rich hydrothermal vent environments where G. bivora thrives, and an apparent V max of 19 ± 5 μ m ·s −1 . Despite using an artificial electron acceptor that does not accurately represent the natural partner or the real energetic system, the enzyme exhibits apparent kinetic parameters that retain biological significance, with a catalytic efficiency within the range expected for functional electron transfer enzymes. Cyc2 TAG1_1 exhibited a redox potential of −130 ± 20 mV vs SHE which is the lowest reported for Cyc2 homologs. The EPR spectrum is consistent with a low‐spin ferric heme with two axial ligands within the protein barrel. These findings provide the first biochemical characterization of Cyc2 TAG1_1 and support its proposed role in iron oxidation.
SN - 2211-5463
SN - 2211-5463
ER -