1PNZ

Crystal structure of ferric citrate transporter FecA in the unliganded form

1PNZ の概要

• エントリーDOI: 10.2210/pdb1pnz/pdb
• 分子名称: Iron(III) dicitrate transport protein fecA precursor (2 entities in total)
• 機能のキーワード: outer membrane protein, beta barrel, tonb-dependent transport, membrane protein
• 由来する生物種: Escherichia coli
• 細胞内の位置: Cell outer membrane: P13036
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 83169.33

構造登録者

Yue, W.W.,Grizot, S.,Buchanan, S.K. (登録日: 2003-06-13, 公開日: 2003-11-18, 最終更新日: 2023-08-16)

主引用文献

Yue, W.W.,Grizot, S.,Buchanan, S.K.
Structural evidence for iron-free citrate and ferric citrate binding to the TonB-dependent outer membrane transporter FecA
J.Mol.Biol., 332:353-368, 2003

PubMed Abstract: Escherichia coli possesses a TonB-dependent transport system, which exploits the iron-binding capacity of citrate and its natural abundance. Here, we describe three structures of the outer membrane ferric citrate transporter FecA: unliganded and complexed with iron-free or diferric dicitrate. We show the structural mechanism for discrimination between the iron-free and ferric siderophore: the binding of diferric dicitrate, but not iron-free dicitrate alone, causes major conformational rearrangements in the transporter. The structure of FecA bound with iron-free dicitrate represents the first structure of a TonB-dependent transporter bound with an iron-free siderophore. Binding of diferric dicitrate to FecA results in changes in the orientation of the two citrate ions relative to each other and in their interactions with FecA, compared to the binding of iron-free dicitrate. The changes in ligand binding are accompanied by conformational changes in three areas of FecA: two extracellular loops, one plug domain loop and the periplasmic TonB-box motif. The positional and conformational changes in the siderophore and transporter initiate two independent events: ferric citrate transport into the periplasm and transcription induction of the fecABCDE transport genes. From these data, we propose a two-step ligand recognition event: FecA binds iron-free dicitrate in the non-productive state or first step, followed by siderophore displacement to form the transport-competent, diferric dicitrate-bound state in the second step.

PubMed: 12948487
DOI: 10.1016/S0022-2836(03)00855-6

実験手法

X-RAY DIFFRACTION (2.5 Å)