1FGH

COMPLEX WITH 4-HYDROXY-TRANS-ACONITATE

1FGH の概要

• エントリーDOI: 10.2210/pdb1fgh/pdb
• 分子名称: ACONITASE, IRON/SULFUR CLUSTER, 4-HYDROXY-ACONITATE ION, ... (4 entities in total)
• 機能のキーワード: lyase, complex
• 由来する生物種: Bos taurus (cattle)
• 細胞内の位置: Mitochondrion: P20004
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 83286.63

構造登録者

Lauble, H.,Kennedy, M.C.,Emptage, M.H.,Beinert, H.,Stout, C.D. (登録日: 1996-09-14, 公開日: 1996-12-23, 最終更新日: 2024-11-20)

主引用文献

Lauble, H.,Kennedy, M.C.,Emptage, M.H.,Beinert, H.,Stout, C.D.
The reaction of fluorocitrate with aconitase and the crystal structure of the enzyme-inhibitor complex.
Proc.Natl.Acad.Sci.USA, 93:13699-13703, 1996

PubMed Abstract: It has been known for many years that fluoroacetate and fluorocitrate when metabolized are highly toxic, and that at least one effect of fluorocitrate is to inactivate aconitase. In this paper we present evidence supporting the hypothesis that the (-)-erythro diastereomer of 2-fluorocitrate acts as a mechanism based inhibitor of aconitase by first being converted to fluoro-cis-aconitate, followed by addition of hydroxide and with loss of fluoride to form 4-hydroxy-trans-aconitate (HTn), which binds very tightly, but not covalently, to the enzyme. Formation of HTn by these reactions is in accord with the working model for the enzyme mechanism. That HTn is the product of fluorocitrate inhibition is supported by the crystal structure of the enzyme-inhibitor complex at 2.05-A resolution, release of fluoride stoichiometric with total enzyme when (-)-erythro-2-fluorocitrate is added, HPLC analysis of the product, slow displacement of HTn by 10(6)-fold excess of isocitrate, and previously published Mössbauer experiments. When (+)-erythro-2-fluorocitrate is added to aconitase, the release of fluoride is stoichiometric with total substrate added, and HPLC analysis of the products indicates the formation of oxalosuccinate, and its derivative alpha-ketoglutarate. This is consistent with the proposed mechanism, as is the formation of HTn from (-)-erythro-2-fluorocitrate. The structure of the inhibited complex reveals that HTn binds like the inhibitor trans-aconitate while providing all the interactions of the natural substrate, isocitrate. The structure exhibits four hydrogen bonds < 2.7 A in length involving HTn, H2O bound to the [4Fe-4S] cluster, Asp-165 and His-167, as well as low temperature factors for these moieties, consistent with the observed very tight binding of the inhibitor.

PubMed: 8942997
DOI: 10.1073/pnas.93.24.13699

実験手法

X-RAY DIFFRACTION (2.05 Å)