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1.
Biotechnol Appl Biochem ; 70(2): 593-602, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35789501

RESUMO

Desiccation tolerance in developing seeds occurs through several mechanisms among which, a common group of proteins named dehydrins has received considerable attention. So far, there is no information dealing with the accumulation of dehydrins in seeds of Opuntia ficus-indica. We have initiated here an extraction protocol based on two critical steps: heat and acid treatments, and the purity of this fraction was analyzed by FTIR spectroscopy. Western blot analysis of the heat-stable protein fraction (HSF) revealed two main bands of approximately 45 and 44 kDa, while three others of ∼40, 32, and 31 kDa were faintly visible, which were recognized by anti-dehydrin antibodies. This fraction exhibited a Cu2+ -dependent resistance to protease treatments. Next, we performed a series of assays to compare the functional properties of the HSF with those of the previously characterized wheat dehydrin (DHN-5). Antibacterial assays revealed that HSF exhibits only moderate antibacterial activities against gram-negative and gram-positive bacteria, with a minimum inhibition concentration ranging from 0.25 to 1 mg/ml. However, in vitro assays revealed that compared to DHN-5, HSF exhibits higher protective activities of the lactate dehydrogenase (LDH) when exposed to heat, freezing, and dehydration stresses. The protective role of HSF seems to be linked to its best ability to minimize protein aggregation.


Assuntos
Opuntia , Opuntia/química , Temperatura Alta , Proteínas de Plantas/farmacologia , Proteínas de Plantas/química , Sementes/química , Antibacterianos/farmacologia , Antibacterianos/metabolismo , Extratos Vegetais/farmacologia , Extratos Vegetais/metabolismo
2.
Phytochemistry ; 213: 113783, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37406790

RESUMO

Dehydrins form the group II LEA protein family and are known to play multiple roles in plant stress tolerance and enzyme protection. They harbor a variable number of conserved lysine rich motifs (K-segments) and may also contain three additional conserved motifs (Y-, F- and S-segments). In this work, we report the isolation and characterization of an FSK2-type dehydrin from the halophytic species Atriplex halimus, which we designate as AhDHN1. In silico analysis of the protein sequence revealed that AhDHN1 contains large number of hydrophilic residues, and is predicted to be intrinsically disordered. In addition, it has an FSK2 architecture with one F-segment, one S-segment, and two K-segments. The expression analysis showed that the AhDHN1 transcript is induced by salt and water stress treatments in the leaves of Atriplex seedlings. Moreover, circular dichroism spectrum performed on recombinant AhDHN1 showed that the dehydrin lacks any secondary structure, confirming its intrinsic disorder nature. However, there is a gain of α-helicity in the presence of membrane-like SDS micelles. In vitro assays revealed that AhDHN1 is able to effectively protect enzymatic activity of the lactate dehydrogenase against cold, heat and dehydration stresses. Our findings strongly suggest that AhDHN1 can be involved in the adaptation mechanisms of halophytes to adverse environments.


Assuntos
Atriplex , Proteínas de Plantas , Proteínas de Plantas/metabolismo , Atriplex/genética , Atriplex/metabolismo , Sequência de Aminoácidos , Plantas/metabolismo , Estrutura Secundária de Proteína
3.
Biomolecules ; 12(2)2022 02 19.
Artigo em Inglês | MEDLINE | ID: mdl-35204830

RESUMO

Dehydrins (DHNs) belong to the LEA (late embryogenesis abundant) family group II, that comprise four conserved motifs (the Y-, S-, F-, and K-segments) and are known to play a multifunctional role in plant stress tolerance. Based on the presence and order of these segments, dehydrins are divided into six subclasses: YnSKn, FnSKn, YnKn, SKn, Kn, and KnS. DHNs are rarely studied in halophytes, and their contribution to the mechanisms developed by these plants to survive in extreme conditions remains unknown. In this work, we carried out multiple genomic analyses of the conservation of halophytic DHN sequences to discover new segments, and examine their architectures, while comparing them with their orthologs in glycophytic plants. We performed an in silico analysis on 86 DHN sequences from 10 halophytic genomes. The phylogenetic tree showed that there are different distributions of the architectures among the different species, and that FSKn is the only architecture present in every plant studied. It was found that K-, F-, Y-, and S-segments are highly conserved in halophytes and glycophytes with a few modifications, mainly involving charged amino acids. Finally, expression data collected for three halophytic species (Puccinillia tenuiflora, Eutrema salsugenium, and Hordeum marinum) revealed that many DHNs are upregulated by salt stress, and the intensity of this upregulation depends on the DHN architecture.


Assuntos
Hordeum , Proteínas de Plantas , Regulação da Expressão Gênica de Plantas , Hordeum/metabolismo , Filogenia , Proteínas de Plantas/metabolismo , Plantas Tolerantes a Sal/genética
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