Plant methionine sulfoxide reductase A and B multigenic families

Abstract

Methionine oxidation to methionine sulfoxide (MetSo), which results in modification of activity and conformation for many proteins, is reversed by an enzyme present in most organisms and termed as methionine sulfoxide reductase (MSR). On the basis of substrate stereospecificity, two types of MSR, A and B, that do not share any sequence similarity, have been identified. In the present review, we first compare the multigenic MSR families in the three plant species for which the genome is fully sequenced: Arabidopsis thaliana, Oryza sativa, and Populus trichocarpa. The MSR gene content is larger in A. thaliana (five MSRAs and nine MSRBs) compared to P. trichocarpa (five MSRAs and four MSRBs) and O. sativa (four MSRAs and three MSRBs). A complete classification based on gene structure, sequence identity, position of conserved reactive cysteines and predicted subcellular localization is proposed. On the basis of in silico and experimental data originating mainly from Arabidopsis, we report that some MSR genes display organ-specific expression patterns and that those encoding plastidic MSRs are highly expressed in photosynthetic organs. We also show that the expression of numerous MSR genes is enhanced by environmental conditions known to generate oxidative stress. Thioredoxins (TRXs) constitute very likely physiological electron donors to plant MSR proteins for the catalysis of MetSO reduction, but the specificity between the numerous TRXs and methionine sulfoxide reductases (MSRs) present in plants remains to be investigated. The essential role of plant MSRs in protection against oxidative damage has been recently demonstrated on transgenic Arabidopsis plants modified in the content of cytosolic or plastidic MSRA.

Evidence for participation of the methionine sulfoxide reductase repair system in plant seed longevity

“…Of note, the abundance of oxidized MSRA.1L was substantially higher in seeds dried either naturally or artificially compared with nondried seeds. The expression of numerous MSR genes is enhanced by environmental conditions known to generate oxidative stress (24); thus, expression of MSRA4 and MSRB2 may be induced by the oxidative context of seed maturation and/or desiccation. Alternatively, MSR expression might be controlled by ABA, which plays a major role in gene expression during seed maturation.…”

“…The role of oxidation of methionine (Met) in methionine sulfoxide (MetO) and its repair by methionine sulfoxide reductases (MSRs) has not been documented in seeds, although several lines of evidence support the possible involvement of MSRs in maturation and germination processes: (i) MSRs belong to the minimal set of proteins required for basic functions in living cells (20); (ii) Met oxidation is a hallmark of oxidative conditions and aging in all organisms (21); (iii) MSRs play a determinant role in the tolerance of oxidative stress (22)(23)(24)(25)(26)(27)(28); and (iv) MSRs control lifespan in microorganisms, insects, and mammals, including human (29)(30)(31)(32). Moreover, one MSR gene exhibits increased expression during reinduction of desiccation tolerance in germinated seeds of Medicago truncatula (33).…”

Comparative Proteomics Analysis Reveals an Intimate Protein Network Provoked by Hydrogen Peroxide Stress in Rice Seedling Leaves

“…Glyoxalase I can convert toxic 2-oxoaldehydes into less reactive 2-hydroxyacids using glutathione as a cofactor (50). The three reductases catalyze the reductions of methoxylated quinine, methionine sulfoxide, and 12-oxophytodienoic acid, respectively (51)(52)(53). Thus, the up-regulation of these proteins implies that the antioxidative defense system is provoked in H 2 O 2 -treated rice seedling leaves, and such a consistent induction is a likely consequence of antioxidative reactions under oxidative stress in plants.…”

Protein Methionine Sulfoxide Dynamics in Arabidopsis thaliana under Oxidative Stress

“…The nine MSRB proteins present in Arabidopsis are also targeted to different organelles: MSRB1 and -B2 are localized in the chloroplast, B3 is designated to the secretory pathway, whereas the other six MSRB proteins are cytosolic (25,26). Also other plants such as poplar with five MSRAs and four MSRBs and rice with four MSRAs and three MSRBs (27) express a considerably larger number of MSR enzymes as compared with mammals, which only contain four MSR genes in total (28). In plants, most of the methionine oxidation studies thus far have focused on the different functions of MSRs rather than on the impact and extent of oxidation of proteinbound methionines (29).…”