Instituto de Bioquímica Vegetal y Fotosíntesis IBVF – CIC Cartuja

URI permanente para esta comunidadhttps://hdl.handle.net/11441/10948

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Exploring the Functional Relationship between y-Type Thioredoxins and 2-Cys Peroxiredoxins in Arabidopsis Chloroplasts
(MDPI, 2020) Jurado Flores, Ana; Delgado Requerey, Victor; Gálvez Ramírez, Alicia; Puerto Galán, Leonor; Pérez Ruiz, Juan Manuel; Cejudo Fernández, Francisco Javier; Universidad de Sevilla. Departamento de Bioquímica Vegetal y Biología Molecular
Thioredoxins (Trxs) are small, ubiquitous enzymes that catalyze disulphide–dithiol interchange in target enzymes. The large set of chloroplast Trxs, including f, m, x and y subtypes, use reducing equivalents fueled by photoreduced ferredoxin (Fdx) for fine-tuning photosynthetic performance and metabolism through the control of the activity of redox-sensitive proteins. Although biochemical analyses suggested functional diversity of chloroplast Trxs, genetic studies have established that deficiency in a particular Trx subtype has subtle phenotypic e ects, leading to the proposal that the Trx isoforms are functionally redundant. In addition, chloroplasts contain an NADPH-dependent Trx reductase with a joint Trx domain, termed NTRC. Interestingly, Arabidopsis mutants combining the deficiencies of x- or f-type Trxs and NTRC display very severe growth inhibition phenotypes, which are partially rescued by decreased levels of 2-Cys peroxiredoxins (Prxs). These findings indicate that the reducing capacity of Trxs f and x is modulated by the redox balance of 2-Cys Prxs, which is controlled by NTRC. In this study, we explored whether NTRC acts as a master regulator of the pool of chloroplast Trxs by analyzing its functional relationship with Trxs y. While Trx y interacts with 2-Cys Prxs in vitro and in planta, the analysis of Arabidopsis mutants devoid of NTRC and Trxs y suggests that Trxs y have only a minor e ect, if any, on the redox state of 2-Cys Prxs.
The Functional Relationship between NADPH Thioredoxin Reductase C, 2-Cys Peroxiredoxins, and m-Type Thioredoxins in the Regulation of Calvin–Benson Cycle and Malate-Valve Enzymes in Arabidopsis
(Multidisciplinary Digital Publishing Institute (MDPI), 2023-05-03) Delgado Requerey, Víctor; Cejudo Fernández, Francisco Javier; González García, María de la Cruz; Universidad de Sevilla. Departamento de Bioquímica Vegetal y Biología Molecular; Ministerio de Ciencia e Innovación (MICIN). España; Junta de Andalucía
The concerted regulation of chloroplast biosynthetic pathways and NADPH extrusion via malate valve depends on f and m thioredoxins (Trxs). The finding that decreased levels of the thiol-peroxidase 2-Cys peroxiredoxin (Prx) suppress the severe phenotype of Arabidopsis mutants lacking NADPH-dependent Trx reductase C (NTRC) and Trxs f uncovered the central function of the NTRC-2-Cys-Prx redox system in chloroplast performance. These results suggest that Trxs m are also regulated by this system; however, the functional relationship between NTRC, 2-Cys Prxs, and m-type Trxs is unknown. To address this issue, we generated Arabidopsis thaliana mutants combining deficiencies in NTRC, 2-Cys Prx B, Trxs m1, and m4. The single trxm1 and trxm4 mutants showed a wild-type phenotype, growth retardation being noticed only in the trxm1m4 double mutant. Moreover, the ntrc-trxm1m4 mutant displayed a more severe phenotype than the ntrc mutant, as shown by the impaired photosynthetic performance, altered chloroplast structure, and defective light-dependent reduction in the Calvin–Benson cycle and malate-valve enzymes. These effects were suppressed by the decreased contents of 2-Cys Prx, since the quadruple ntrc-trxm1m4-2cpb mutant displayed a wild-type-like phenotype. These results show that the activity of m-type Trxs in the light-dependent regulation of biosynthetic enzymes and malate valve is controlled by the NTRC-2-Cys-Prx system.

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Examinando Instituto de Bioquímica Vegetal y Fotosíntesis IBVF – CIC Cartuja por Materia "2-Cys peroxiredoxin"