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Morán Juez, José Fernando

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https://academica-e.unavarra.es/handle/2454/49610

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Morán Juez

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José Fernando

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Ciencias

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IMAB. Research Institute for Multidisciplinary Applied Biology

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0000-0001-6621-6961

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3087

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2022 - 20242
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Author: Esteban Terradillos, Raquel × Start date: 2020 × End date: 2024 × Has files: true ×

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    PublicationOpen Access
    The importance of the urea cycle and its relationships to polyamine metabolism during ammonium stress in Medicago truncatula
    (Oxford University Press, 2022) Urra Rodríguez, Marina; Buezo Bravo, Javier; Royo Castillejo, Beatriz; Cornejo Ibergallartu, Alfonso; López Gómez, Pedro; Cerdán Ruiz, Daniel; Esteban Terradillos, Raquel; Martínez Merino, Víctor; Gogorcena, Yolanda; Tavladoraki, Paraskevi; Morán Juez, José Fernando; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Institute for Multidisciplinary Research in Applied Biology - IMAB; Ciencias; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa; Gobierno de Navarra / Nafarroako Gobernuaren
    The ornithine–urea cycle (urea cycle) makes a signifcant contribution to the metabolic responses of lower photosynthetic eukaryotes to episodes of high nitrogen availability. In this study, we compared the role of the plant urea cycle and its relationships to polyamine metabolism in ammonium-fed and nitrate-fed Medicago truncatula plants. High ammonium resulted in the accumulation of ammonium and pathway intermediates, particularly glutamine, arginine, ornithine, and putrescine. Arginine decarboxylase activity was decreased in roots, suggesting that the ornithine decarboxylase-dependent production of putrescine was important in situations of ammonium stress. The activity of copper amine oxidase, which releases ammonium from putrescine, was signifcantly decreased in both shoots and roots. In addition, physiological concentrations of ammonium inhibited copper amine oxidase activity in in vitro assays, supporting the conclusion that high ammonium accumulation favors putrescine synthesis. Moreover, early supplementation of plants with putrescine avoided ammonium toxicity. The levels of transcripts encoding urea-cyclerelated proteins were increased and transcripts involved in polyamine catabolism were decreased under high ammonium concentrations. We conclude that the urea cycle and associated polyamine metabolism function as important protective mechanisms limiting ammonium toxicity in M. truncatula. These fndings demonstrate the relevance of the urea cycle to polyamine metabolism in higher plants.
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    A new oxidative pathway of nitric oxide production from oximes in plants
    (Cell Press, 2024) López Gómez, Pedro; Buezo Bravo, Javier; Urra Rodríguez, Marina; Cornejo Ibergallartu, Alfonso; Esteban Terradillos, Raquel; Fernández de los Reyes, Jorge; Urarte Rodríguez, Estíbaliz; Rodríguez-Dobreva, Estefanía; Chamizo Ampudia, Alejandro; Eguaras, Alejandro; Wolf, Sebastian; Marino Bilbao, Daniel; Martínez Merino, Víctor; Morán Juez, José Fernando; Ciencias; Zientziak; Institute for Multidisciplinary Research in Applied Biology - IMAB; Institute for Advanced Materials and Mathematics - INAMAT2
    Nitric oxide (NO) is an essential reactive oxygen species and a signal molecule in plants. Although several studies have proposed the occurrence of oxidative NO production, only reductive routes for NO production, such as the nitrate (NO-3) -upper-reductase pathway, have been evidenced to date in land plants. However, plants grown axenically with ammonium as the sole source of nitrogen exhibit contents of nitrite and NO3, evidencing the existence of a metabolic pathway for oxidative production of NO. We hypothesized that ox- imes, such as indole-3-acetaldoxime (IAOx), a precursor to indole-3-acetic acid, are intermediate oxidation products in NO synthesis. We detected the production of NO from IAOx and other oximes catalyzed by peroxidase (POD) enzyme using both 4-amino-5-methylamino-20,70-difluorescein fluorescence and chem- iluminescence. Flavins stimulated the reaction, while superoxide dismutase inhibited it. Interestingly, mouse NO synthase can also use IAOx to produce NO at a lower rate than POD. We provided a full mech- anism for POD-dependent NO production from IAOx consistent with the experimental data and supported by density functional theory calculations. We showed that the addition of IAOx to extracts from Medicago truncatula increased the in vitro production of NO, while in vivo supplementation of IAOx and other oximes increased the number of lateral roots, as shown for NO donors, and a more than 10-fold increase in IAOx dehydratase expression. Furthermore, we found that in vivo supplementation of IAOx increased NO pro- duction in Arabidopsis thaliana wild-type plants, while prx33-34 mutant plants, defective in POD33-34, had reduced production. Our data show that the release of NO by IAOx, as well as its auxinic effect, explain the superroot phenotype. Collectively, our study reveals that plants produce NO utilizing diverse molecules such as oximes, POD, and flavins, which are widely distributed in the plant kingdom, thus intro- ducing a long-awaited oxidative pathway to NO production in plants. This knowledge has essential impli- cations for understanding signaling in biological systems.