22XO

Cryo-EM structure of E.coli LrhA

22XO の概要

• エントリーDOI: 10.2210/pdb22xo/pdb
• EMDBエントリー: 68756
• 分子名称: Probable HTH-type transcriptional regulator LrhA (1 entity in total)
• 機能のキーワード: lysr-type, flagellar biosynthesis, transcriptional factor, transcription
• 由来する生物種: Escherichia coli
• タンパク質・核酸の鎖数: 4
• 化学式量合計: 147192.36

構造登録者

Niu, B.,Kikkawa, M.,Jiang, X. (登録日: 2026-01-27, 公開日: 2026-02-11, 最終更新日: 2026-03-11)

主引用文献

Niu, B.,Kikkawa, M.,Jiang, X.
Oligomerization-Dependent Regulation of LrhA Controls Bacterial Flagellar Biosynthesis.
J.Mol.Biol., 438:169682-169682, 2026

PubMed Abstract: LysR-type transcriptional regulators (LTTRs) are a diverse family of proteins that regulate various cellular processes, including motility in bacteria. In Escherichia coli, the LTTR LrhA represses flagellar biosynthesis by inhibiting the flhDC operon. However, the structural basis underlying this regulation has remained unclear. Here, we determined both a high-resolution crystal structure and a cryo-EM reconstruction of LrhA, revealing a predominant and stable tetrameric organization with pronounced structural variability in its effector-binding region. Structural and biochemical analyses demonstrate that mutations in these variable regions perturb the oligomeric equilibrium of LrhA, shifting the balance between tetrameric and dimeric species. This shift correlates with enhanced DNA binding affinity and stronger repression of the flhDC promoter. While ligand binding may similarly modulate LrhA activity, our data primarily support a model in which alterations in oligomeric state mediated by the variable regions regulate LrhA function. Together, these findings provide a structural framework for understanding how LrhA controls bacterial motility and offer broader insights into oligomerization-based regulation within the LTTR family.

PubMed: 41655832
DOI: 10.1016/j.jmb.2026.169682

実験手法

ELECTRON MICROSCOPY (2.72 Å)