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Communication Dans Un Congrès Année : 2021

Methionine sulfoxide reductases: redox control of protein function and protection against oxidative stress.

Lionel Tarrago

Résumé

Methionine, either as a free amino acid or included in proteins, can be oxidized into methionine sulfoxide (MetO), which exists as R and S diastereomers. Almost all characterized organisms possess thiol-oxidoreductases enzymes named methionine sulfoxide reductases (Msr) to reduce MetO back to Met. MsrA and MsrB reduce the S and R diastereomers of MetO, respectively, with strict stereospecificity. MsrA can act similarly on the free amino acid and oxidized proteins, whereas MsrB reduces efficiently only protein-bound MetO. Another type of thiol-oxidoreductase, the free-methionine-R-sulfoxide reductase (fRMsr), identified in prokaryotes and fungi, reduces the R diastereomer of the free amino acid MetO only. These MetO reducing enzymes are partners of thioredoxins and glutaredoxins, from which they receive reducing power. All these Msrs play important roles in the protection of organisms against oxidative stress through two main functions: i) the repair of oxidized proteins, and ii) an antioxidant function through reactive oxygen species scavenging by cyclic Met oxidation and reduction. Moreover, the reversible Met oxidation was shown to act as a post-translational modification responsible for the activation of enzymes and transcription factors or the regulation of protein-protein interactions. Some bacteria possess molybdenum-containing enzymes that reduce MetO, either in the free or protein-bound forms. Among these, the periplasmic MsrP reduces efficiently protein-bound MetO without stereospecificity. After a journey in the Msr world, I will present you the latest results about the periplasmic systems of MetO reduction in the purple bacteria Rhodobacter sphaeroides.

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hal-03522933 , version 1 (12-01-2022)

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  • HAL Id : hal-03522933 , version 1

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Lionel Tarrago. Methionine sulfoxide reductases: redox control of protein function and protection against oxidative stress.. Club oxydase 2021, 2021, Grenoble, France. ⟨hal-03522933⟩
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