7WIF

The THF-II riboswitch bound to H4B

7WIF の概要

• エントリーDOI: 10.2210/pdb7wif/pdb
• 分子名称: RNA (50-MER), 5,6,7,8-TETRAHYDROBIOPTERIN (2 entities in total)
• 機能のキーワード: holo form, rna
• 由来する生物種: Mesorhizobium loti
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 16528.84

構造登録者

Xu, L.,Fang, X.,Xiao, Y. (登録日: 2022-01-03, 公開日: 2023-01-18, 最終更新日: 2024-05-29)

主引用文献

Xu, L.,Xiao, Y.,Zhang, J.,Fang, X.
Structural insights into translation regulation by the THF-II riboswitch.
Nucleic Acids Res., 51:952-965, 2023

PubMed Abstract: In bacteria, expression of folate-related genes is controlled by the tetrahydrofolate (THF) riboswitch in response to specific binding of THF and its derivatives. Recently, a second class of THF riboswitches, named THF-II, was identified in Gram-negative bacteria, which exhibit distinct architecture from the previously characterized THF-I riboswitches found in Gram-positive bacteria. Here, we present the crystal structures of the ligand-bound THF-II riboswitch from Mesorhizobium loti. These structures exhibit a long rod-like fold stabilized by continuous base pair and base triplet stacking across two helices of P1 and P2 and their interconnecting ligand-bound binding pocket. The pterin moiety of the ligand docks into the binding pocket by forming hydrogen bonds with two highly conserved pyrimidines in J12 and J21, which resembles the hydrogen-bonding pattern at the ligand-binding site FAPK in the THF-I riboswitch. Using small-angle X-ray scattering and isothermal titration calorimetry, we further characterized the riboswitch in solution and reveal that Mg2+ is essential for pre-organization of the binding pocket for efficient ligand binding. RNase H cleavage assay indicates that ligand binding reduces accessibility of the ribosome binding site in the right arm of P1, thus down-regulating the expression of downstream genes. Together, these results provide mechanistic insights into translation regulation by the THF-II riboswitch.

PubMed: 36620887
DOI: 10.1093/nar/gkac1257

実験手法

X-RAY DIFFRACTION (2.86 Å)