Dataset Information

Localization and Dynamics of the Methionine Sulfoxide Reductases MsrB1 and MsrB2 in Beech Seeds.

ABSTRACT: Beech seeds are produced irregularly, and there is a need for long-term storage of these seeds for forest management practices. Accumulated reactive oxygen species broadly oxidize molecules, including amino acids, such as methionine, thereby contributing to decreased seed viability. Methionine oxidation can be reversed by the activity of methionine sulfoxide reductases (Msrs), which are enzymes involved in the regulation of many developmental processes and stress responses. Two types of Msrs, MsrB1 and MsrB2, were investigated in beech seeds to determine their abundance and localization. MsrB1 and MsrB2 were detected in the cortical cells and the outer area of the vascular cylinder of the embryonic axes as well as in the epidermis and parenchyma cells of cotyledons. The abundances of MsrB1 and MsrB2 decreased during long-term storage. Ultrastructural analyses have demonstrated the accumulation of these proteins in protein storage vacuoles and in the cytoplasm, especially in close proximity to the cell membrane. In silico predictions of possible Msr interactions supported our findings. In this study, we investigate the contribution of MsrB1 and MsrB2 locations in the regulation of seed viability and suggest that MsrB2 is linked with the longevity of beech seeds via association with proper utilization of storage material.

SUBMITTER: Wojciechowska N

PROVIDER: S-EPMC7795007 | biostudies-literature | 2021 Jan

REPOSITORIES: biostudies-literature

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Localization and Dynamics of the Methionine Sulfoxide Reductases MsrB1 and MsrB2 in Beech Seeds.

Wojciechowska Natalia N Bagniewska-Zadworna Agnieszka A Minicka Julia J Michalak Kornel M KM Kalemba Ewa M EM

International journal of molecular sciences 20210102 1

Beech seeds are produced irregularly, and there is a need for long-term storage of these seeds for forest management practices. Accumulated reactive oxygen species broadly oxidize molecules, including amino acids, such as methionine, thereby contributing to decreased seed viability. Methionine oxidation can be reversed by the activity of methionine sulfoxide reductases (Msrs), which are enzymes involved in the regulation of many developmental processes and stress responses. Two types of Msrs, Ms ...[more]

PMID: 33401671

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Project description:Methionine residues in proteins are susceptible to oxidation by reactive oxygen species, but can be repaired via reduction of the resulting methionine sulfoxides by methionine-S-sulfoxide reductase (MsrA) and methionine-R-sulfoxide reductase (MsrB). However, the identity of all methionine sulfoxide reductases involved, their cellular locations and relative contributions to the overall pathway are poorly understood. Here, we describe a methionine-R-sulfoxide reduction system in mammals, in which two MsrB homologues were previously described. We found that human and mouse genomes possess three MsrB genes and characterized their protein products, designated MsrB1, MsrB2, and MsrB3. MsrB1 (Selenoprotein R) was present in the cytosol and nucleus and exhibited the highest methionine-R-sulfoxide reductase activity because of the presence of selenocysteine (Sec) in its active site. Other mammalian MsrBs contained cysteine in place of Sec and were less catalytically efficient. MsrB2 (CBS-1) resided in mitochondria. It had high affinity for methionine-R-sulfoxide, but was inhibited by higher concentrations of the substrate. The human MsrB3 gene gave rise to two protein forms, MsrB3A and MsrB3B. These were generated by alternative splicing that introduced contrasting N-terminal and C-terminal signals, such that MsrB3A was targeted to the endoplasmic reticulum and MsrB3B to mitochondria. We found that only mitochondrial forms of mammalian MsrBs (MsrB2 and MsrB3B) could compensate for MsrA and MsrB deficiency in yeast. All mammalian MsrBs belonged to a group of zinc-containing proteins. The multiplicity of MsrBs contrasted with the presence of a single mammalian MsrA gene as well as with the occurrence of single MsrA and MsrB genes in yeast, fruit flies, and nematodes. The data suggested that different cellular compartments in mammals maintain a system for repair of oxidized methionine residues and that this function is tuned in enzyme- and stereo-specific manner.

Project description:Beech trees produce seeds irregularly, necessitating the storage of these seeds for forestation. Despite the acquisition of desiccation tolerance during development, beech seeds lose viability during long-term storage faster than orthodox-type seeds. Seeds stored for short (3 years) and long (20 years) periods under optimal conditions were compared. Aged seeds characterized with germination capacity reduced to 30% displayed increased membrane damage, manifested as electrolyte leakage and lipid peroxidation levels. Analyses have been based on embryonic axes containing higher levels of reactive oxygen species (ROS) and higher levels of protein-bound methionine sulfoxide (MetO) in aged seeds. Using gel-free shotgun proteomics, 3,949 proteins were identified and 2,442 were reliably quantified to indicate 25 proteins with upregulated abundance and 35 with downregulated abundance in beech seeds under long-term storage compared to those under short-term storage. Functional analyses based on gene ontology annotations revealed that nucleic acid binding activity (biological process), hydrolases (molecular function), ribosome organization or biogenesis and transmembrane transport (cellular processes), and ATP synthesis (pathway) were affected in aged seeds. To verify whether MetO the oxidative posttranslational modification of proteins reversed via the action of methionine sulfoxide reductase (Msr) enzymes is involved in ageing of beech seeds we identified 316 and reliably quantified 226 MetO-containing proteins, among which 9 and 19 exhibited significantly up- and downregulated MetO levels, respectively, in beech seeds under long-term storage. Several Msr isoforms were identified and recognized as MsrA1-like, MsrA4, MsrB5 and MsrB5-like in beech seeds. Only MsrA1-like displayed decreased abundance in aged seeds. We demonstrated that the loss of membrane integrity reflected in elevated abundance of membrane proteins had higher impact on seed ageing progress rather than MetO/Msr system.

Dataset Information

Localization and Dynamics of the Methionine Sulfoxide Reductases MsrB1 and MsrB2 in Beech Seeds.

Publications

Localization and Dynamics of the Methionine Sulfoxide Reductases MsrB1 and MsrB2 in Beech Seeds.

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