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1.
Sci Rep ; 9(1): 17217, 2019 11 20.
Artigo em Inglês | MEDLINE | ID: mdl-31748604

RESUMO

The bacterium Deinococcus radiodurans is highly resistant to several stress conditions, such as radiation. According to several reports, manganese plays a crucial role in stress protection, and a high Mn/Fe ratio is essential in this process. However, mobilization of manganese and iron, and the role of DNA-binding-proteins-under-starved-conditions during oxidative-stress remained open questions. We used synchrotron-based X-ray fluorescence imaging at nano-resolution to follow element-relocalization upon stress, and its dependency on the presence of Dps proteins, using dps knockout mutants. We show that manganese, calcium, and phosphorus are mobilized from rich-element regions that resemble electron-dense granules towards the cytosol and the cellular membrane, in a Dps-dependent way. Moreover, iron delocalizes from the septum region to the cytoplasm affecting cell division, specifically in the septum formation. These mechanisms are orchestrated by Dps1 and Dps2, which play a crucial role in metal homeostasis, and are associated with the D. radiodurans tolerance against reactive oxygen species.


Assuntos
Proteínas de Bactérias/metabolismo , Citoproteção/efeitos dos fármacos , Deinococcus/crescimento & desenvolvimento , Ferro/metabolismo , Manganês/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Paraquat/farmacologia , Proteínas de Bactérias/genética , Deinococcus/efeitos dos fármacos , Herbicidas/farmacologia , Espécies Reativas de Oxigênio/metabolismo
2.
J Exp Bot ; 69(19): 4633-4649, 2018 08 31.
Artigo em Inglês | MEDLINE | ID: mdl-30053161

RESUMO

Post-translational modifiers such as the small ubiquitin-like modifier (SUMO) peptide act as fast and reversible protein regulators. Functional characterization of the sumoylation machinery has determined the key regulatory role that SUMO plays in plant development. Unlike components of the SUMO conjugation pathway, SUMO proteases (ULPs) are encoded by a relatively large gene family and are potential sources of specificity within the pathway. This study reports a thorough comparative genomics and phylogenetic characterization of plant ULPs, revealing the presence of one ULP1-like and three ULP2-like SUMO protease subgroups within plant genomes. As representatives of an under-studied subgroup, Arabidopsis SPF1 and SPF2 were subjected to functional characterization. Loss-of-function mutants implicated both proteins with vegetative growth, flowering time, and seed size and yield. Mutants constitutively accumulated SUMO conjugates, and yeast complementation assays associated these proteins with the function of ScUlp2 but not ScUlp1. Fluorescence imaging placed both proteins in the plant cell nucleoplasm. Transcriptomics analysis indicated strong regulatory involvement in secondary metabolism, cell wall remodelling, and nitrate assimilation. Furthermore, developmental defects of the spf1-1 spf2-2 (spf1/2) double-mutant opposed those of the major E3 ligase siz1 mutant and, most significantly, developmental and transcriptomic characterization of the siz1 spf1/2 triple-mutant placed SIZ1 as epistatic to SPF1 and SPF2.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Cisteína Endopeptidases/genética , Ligases/genética , Sequência de Aminoácidos , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/metabolismo , Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/metabolismo , Parede Celular/metabolismo , Cisteína Endopeptidases/química , Cisteína Endopeptidases/metabolismo , Ligases/metabolismo , Filogenia , Alinhamento de Sequência , Proteínas Modificadoras Pequenas Relacionadas à Ubiquitina/genética , Proteínas Modificadoras Pequenas Relacionadas à Ubiquitina/metabolismo
3.
Acta Crystallogr F Struct Biol Commun ; 70(Pt 5): 669-72, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24817734

RESUMO

Manganese superoxide dismutase (MnSOD) is an essential primary antioxidant enzyme. MnSOD plays an important role in plant tolerance to abiotic stress and is a target candidate for increasing stress tolerance in crop plants. Although the structure and kinetic parameters of MnSODs from several organisms have been determined, this information is still lacking for plant MnSODs. Here, recombinant MnSOD from Arabidopsis thaliana (AtMnSOD) was expressed, purified and crystallized. A nearly complete data set could only be obtained when a total rotation range of 180° was imposed during data collection, despite the seemingly tetragonal metric of the AtMnSOD crystal diffraction. The data set extended to 1.95 Å resolution and the crystal belonged to space group P1. Molecular-replacement calculations using an ensemble of homologous SOD structures as a search model gave a unique and unambiguous solution corresponding to eight molecules in the asymmetric unit. Structural and kinetic analysis of AtMnSOD is currently being undertaken.


Assuntos
Arabidopsis/enzimologia , Regulação Enzimológica da Expressão Gênica , Superóxido Dismutase/biossíntese , Superóxido Dismutase/isolamento & purificação , Cristalização , Superóxido Dismutase/química
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