Examinando por Autor "Barahona , Emma"

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Azotobacter vinelandii scaffold protein NifU transfers iron to NifQ as part of the iron-molybdenum cofactor biosynthesis pathway for nitrogenase
(Elsevier, 2024-10-22) Barahona , Emma; Collanstes García, Juan Andrés; Rosa-Núñez, Elena; Xiong, Jin; Jiang, Xi; Jiménez-Vicente, Emilio; Echávarri-Erasun, Carlos; Guo, Yisong; Rubio, Luis M; González-Guerrero, Manuel
The Azotobacter vinelandii molybdenum nitrogenase obtains molybdenum from NifQ, a monomeric iron-sulfur molybdoprotein. This protein requires an existing [Fe-S] cluster to form a [Mo-Fe3-S4] group, which acts as a specific molybdenum donor during nitrogenase FeMo-co biosynthesis. Here, we show biochemical evidence supporting the role of NifU as the [Fe-S] cluster donor. Protein-protein interaction studies involving apo-NifQ and as-isolated NifU demonstrated their interaction, which was only effective when NifQ lacked its [Fe-S] cluster. Incubation of apo-NifQ with [Fe4-S4]-loaded NifU increased the iron content of the former, contingent on both proteins being able to interact with one another. As a result of this interaction, a [Fe4-S4] cluster was transferred from NifU to NifQ. In A. vinelandii, NifQ was preferentially metalated by NifU rather than by the [Fe-S] cluster scaffold protein IscU. These results indicate the necessity of co-expressing NifU and NifQ to efficiently provide molybdenum for FeMo-co biosynthesis when engineering nitrogenase in plants.
Towards biohydrogen overproduction and valorization of food waste by genetic engineering of Rhodobacter capsulatus
(2024-09) Valverde- Cañas, Ángel; Cuesta- Belvis, Daniel; Cicimov, Viktor; de Nicolás, Amanda P.; Díez, Mario P.; Díaz, Elena; de la Rubia, María Ángeles; Mohedano, Ángel F.; Puyol, Daniel; Barahona , Emma
Non-sulfur red bacteria, such as Rhodobacter capsulatus, produce H2 through photofermentation via nitrogenase. These bacteria offer several advantages over other hydrogen bioproduction systems, including high substrate conversion efficiency, the use of a wide variety of carbon sources, the ability to operate under environmental conditions, reduced energy consumption, and high purity of the hydrogen produced. Despite these advantages, higher production rates and more economical carbon sources are required to compete with conventional H2 production methods. For this reason, our ongoing work focuses on two main objectives: genetically redesigning R. capsulatus to increase its H2 production rates, and optimizing and improving the process by valorizing the material and energy content of food waste. In the H2 production experiments with R. capsulatus, both the wild-type strain and a mutant defective in uptake hydrogenase (ΔhupAB) were evaluated. Process water obtained from the hydrothermal carbonization of food waste and a minimal RCV medium were used as substrates in the photofermentation process. The experiments were carried out in batch mode under continuous illumination. The highest levels of H2 production were observed under the condition where the hupAB mutant was growing in RCV medium without a nitrogen source (almost 110 mL of H2/gCOD). However, H2 production values were similar to those obtained using process water as a substrate during the first 24 hours, thereby demonstrating that R. capsulatus can produce H2 from food waste.