8G64

Heme-bound flavodoxin FldH from Fusobacterium nucleatum

8G64 の概要

• エントリーDOI: 10.2210/pdb8g64/pdb
• 分子名称: Flavodoxin, FLAVIN MONONUCLEOTIDE, PROTOPORPHYRIN IX CONTAINING FE, ... (5 entities in total)
• 機能のキーワード: anaerobilin, fmn-containing flavodoxin, heme acquisition chaperone, hmuf homolog, flavoprotein
• 由来する生物種: Fusobacterium nucleatum
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 20768.49

構造登録者

Chan, A.C.,Wolthers, K.R.,Murphy, M.E. (登録日: 2023-02-14, 公開日: 2023-08-09, 最終更新日: 2024-05-22)

主引用文献

McGregor, A.K.,Chan, A.C.K.,Schroeder, M.D.,Do, L.T.M.,Saini, G.,Murphy, M.E.P.,Wolthers, K.R.
A new member of the flavodoxin superfamily from Fusobacterium nucleatum that functions in heme trafficking and reduction of anaerobilin.
J.Biol.Chem., 299:104902-104902, 2023

PubMed Abstract: Fusobacterium nucleatum is an opportunistic oral pathogen that is associated with various cancers. To fulfill its essential need for iron, this anaerobe will express heme uptake machinery encoded at a single genetic locus. The heme uptake operon includes HmuW, a class C radical SAM-dependent methyltransferase that degrades heme anaerobically to release Fe and a linear tetrapyrrole called anaerobilin. The last gene in the operon, hmuF encodes a member of the flavodoxin superfamily of proteins. We discovered that HmuF and a paralog, FldH, bind tightly to both FMN and heme. The structure of Fe-heme-bound FldH (1.6 Å resolution) reveals a helical cap domain appended to the ⍺/β core of the flavodoxin fold. The cap creates a hydrophobic binding cleft that positions the heme planar to the si-face of the FMN isoalloxazine ring. The ferric heme iron is hexacoordinated to His134 and a solvent molecule. In contrast to flavodoxins, FldH and HmuF do not stabilize the FMN semiquinone but instead cycle between the FMN oxidized and hydroquinone states. We show that heme-loaded HmuF and heme-loaded FldH traffic heme to HmuW for degradation of the protoporphyrin ring. Both FldH and HmuF then catalyze multiple reductions of anaerobilin through hydride transfer from the FMN hydroquinone. The latter activity eliminates the aromaticity of anaerobilin and the electrophilic methylene group that was installed through HmuW turnover. Hence, HmuF provides a protected path for anaerobic heme catabolism, offering F. nucleatum a competitive advantage in the colonization of anoxic sites of the human body.

PubMed: 37302554
DOI: 10.1016/j.jbc.2023.104902

実験手法

X-RAY DIFFRACTION (1.6 Å)