Iron–sulfur biology invades tRNA modification: the case of U34 sulfuration

Abstract Sulfuration of uridine 34 in the anticodon tRNAs is conserved three domains life, guaranteeing fidelity protein translation. In eubacteria, it catalyzed by MnmA-type enzymes, which were previously concluded not to depend on an iron–sulfur [Fe–S] cluster. However, we report here spectroscopic and iron/sulfur analysis, as well vitro catalytic assays site-directed mutagenesis studies unambiguously showing that MnmA from Escherichia coli can bind a [4Fe–4S] cluster, essential for sulfuration U34-tRNA. We propose cluster serves activate hydrosulfide nucleophilic attack adenylated nucleoside. Intriguingly, found E. cells retain s2U34 biosynthesis ΔiscUA ΔsufABCDSE strain, lacking functional ISC SUF assembly machineries, thus suggesting original yet undescribed way maturation MnmA. Moreover, genetic analysis importance sustaining oxidative stress.