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Cytochrome c Catalyzes the Hydrogen Peroxide‐Assisted Oxidative Desulfuration of 2‐Thiouridines in Transfer RNAs
Author(s) -
Sierant Małgorzata,
Kulik Katarzyna,
Sochacka Elzbieta,
Szewczyk Rafal,
Sobczak Milena,
Nawrot Barbara
Publication year - 2018
Publication title -
chembiochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.05
H-Index - 126
eISSN - 1439-7633
pISSN - 1439-4227
DOI - 10.1002/cbic.201700692
Subject(s) - chemistry , transfer rna , hydrogen peroxide , sulfenic acid , oxidative phosphorylation , uridine , biochemistry , stereochemistry , rna , cytochrome p450 , cytochrome c , nucleoside , enzyme , cysteine , mitochondrion , gene
Abstract The 5‐substituted 2‐thiouridines (R5S2Us) present in the first (wobble) position of the anticodon of transfer RNAs (tRNAs) contribute to accuracy in reading mRNA codons and tuning protein synthesis. Previously, we showed that, under oxidative stress conditions in vitro, R5S2Us were sensitive to hydrogen peroxide (H 2 O 2 ) and that their oxidative desulfuration produced 5‐substituted uridines (R5Us) and 4‐pyrimidinone nucleosides (R5H2Us) at a ratio that depended on the pH and an R5 substituent. Here, we demonstrate that the desulfuration of 2‐thiouridines, either alone or within an RNA/tRNA chain, is catalyzed by cytochrome c (cyt c ). Its kinetics are similar to those of Fenton‐type catalytic 2‐thiouridine (S2U) desulfuration. Cyt c /H 2 O 2 ‐ and Fe II ‐mediated reactions deliver predominantly 4‐pyrimidinone nucleoside (H2U)‐type products. The pathway of the cyt c /H 2 O 2 ‐peroxidase‐mediated S2U→H2U transformation through uridine sulfenic (U‐SOH), sulfinic (U‐SO 2 H), and sulfonic (U‐SO 3 H) intermediates is confirmed by LC–MS. The cyt c /H 2 O 2 ‐mediated oxidative damage of S2U‐tRNA may have biological relevance through alteration of the cellular functions of transfer RNA.