Abstract
The tRNA ligase complex (tRNA-LC) splices precursor tRNAs (pre-tRNA), and Xbp1-mRNA during the unfolded protein response (UPR). In aerobic conditions, a cysteine residue bound to two metal ions in its ancient, catalytic subunit RTCB could make the tRNA-LC susceptible to oxidative inactivation. Here, we confirm this hypothesis and reveal a co-evolutionary association between the tRNA-LC and PYROXD1, a conserved and essential oxidoreductase. We reveal that PYROXD1 preserves the activity of the mammalian tRNA-LC in pre-tRNA splicing and UPR. PYROXD1 binds the tRNA-LC in the presence of NAD(P)H and converts RTCB-bound NAD(P)H into NAD(P)+, a typical oxidative co-enzyme. However, NAD(P)+ here acts as an antioxidant and protects the tRNA-LC from oxidative inactivation, which is dependent on copper ions. Genetic variants of PYROXD1 that cause human myopathies only partially support tRNA-LC activity. Thus, we establish the tRNA-LC as an oxidation-sensitive metalloenzyme, safeguarded by the flavoprotein PYROXD1 through an unexpected redox mechanism.
Original language | English |
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Pages (from-to) | 2520-2532.e16 |
Journal | Molecular Cell |
Volume | 81 |
Issue number | 12 |
Early online date | 29 Apr 2021 |
DOIs | |
Publication status | Published - 17 Jun 2021 |
Keywords
- copper
- metalloenzyme
- myopathy
- NADH
- NADPH
- oxidative stress
- oxidoreductase
- pre-tRNA splicing
- PYROXD1
- RtcB
- tRNA ligase complex
- UPR