8IFX

Aquifex aeolicus TsaD-TsaB in complex with ADP

Summary for 8IFX

• Entry DOI: 10.2210/pdb8ifx/pdb
• Related: 8IEY
• Descriptor: tRNA N6-adenosine threonylcarbamoyltransferase, Gcp-like domain-containing protein, FE (III) ION, ... (6 entities in total)
• Functional Keywords: trna t6a-modifying enzyme, tsad-tsab complex, transferase
• Biological source: Aquifex aeolicus; More
• Total number of polymer chains: 2
• Total formula weight: 61308.39

Authors

Lu, S.Z.,Zhang, W.H. (deposition date: 2023-02-20, release date: 2024-03-20, Last modification date: 2024-12-11)

Primary citation

Lu, S.,Jin, M.,Yu, Z.,Zhang, W.
Structure-function analysis of tRNA t 6 A-catalysis, assembly, and thermostability of Aquifex aeolicus TsaD 2 B 2 tetramer in complex with TsaE.
J.Biol.Chem., 300:107962-107962, 2024

PubMed Abstract: The universal N-threonylcarbamoyladenosine (tA) at position 37 of tRNAs is one of core post-transcriptional modifications that are needed for promoting translational fidelity. In bacteria, TsaC utilizes L-threonine, bicarbonate and ATP to generate an intermediate threonylcarbamoyladenylate (TC-AMP), of which the TC-moiety is transferred to N6 atom of tRNA A37 to generate tA by TsaD with support of TsaB and TsaE. TsaD and TsaB form a TsaDB dimer to which tRNA and TsaE are competitively bound. The catalytic mechanism of TsaD and auxiliary roles of TsaB and TsaE remain to be fully elucidated. In this study, we reconstituted tRNA tA biosynthesis using recombinant TsaC, TsaD-TsaB and TsaE from thermophilic Aquifex aeolicus and determined crystal structures of apo-form and ADP-bound form of TsaDB tetramer. Our TsaDB-TsaE-tRNA model coupled functional validations reveal that the binding of tRNA or TsaE to TsaDB is regulated by C-terminal tail of TsaB and a helical hairpin α1-α2 of TsaD. A. aeolicus TsaDB or TsaDB possesses a basal divalent ion-dependent tA-catalytic activity that is stimulated by TsaE at the cost of ATP consumption. Our data suggest that binding of TsaE to TsaDB induces conformational changes of α1, α2, α6, α7 and α8 of TsaD and C-terminal tail of TsaB, leading to release of tRNA tA and AMP. ATP hydrolysis-driven dissociation of TsaE from TsaDB resets an active conformation of TsaDB. Dimerization of thermophilic TsaDB enhances thermostability and promotes tA-catalytic activity of TsaDB-tRNA, of which GC base pairs in anticodon stem are needed for correct folding of thermophilic tRNA at higher temperatures.

PubMed: 39510188
DOI: 10.1016/j.jbc.2024.107962

Experimental method

X-RAY DIFFRACTION (2 Å)