3A5S

Benzalacetone synthase (I207L/L208F)

3A5S の概要

• エントリーDOI: 10.2210/pdb3a5s/pdb
• 関連するPDBエントリー: 1CGK 1U0U 2D3M 3A5Q 3A5R
• 分子名称: Benzalacetone synthase (2 entities in total)
• 機能のキーワード: benzalacetone synthase, chalcone synthase, type iii polyketide synthase, transferase, acyltransferase
• 由来する生物種: Rheum palmatum
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 85039.92

構造登録者

Morita, H.,Kato, R.,Abe, I.,Sugio, S.,Kohno, T. (登録日: 2009-08-10, 公開日: 2010-01-26, 最終更新日: 2023-11-01)

主引用文献

Morita, H.,Shimokawa, Y.,Tanio, M.,Kato, R.,Noguchi, H.,Sugio, S.,Kohno, T.,Abe, I.
A structure-based mechanism for benzalacetone synthase from Rheum palmatum
Proc.Natl.Acad.Sci.USA, 107:669-673, 2010

PubMed Abstract: Benzalacetone synthase (BAS), a plant-specific type III polyketide synthase (PKS), catalyzes a one-step decarboxylative condensation of malonyl-CoA and 4-coumaroyl-CoA to produce the diketide benzalacetone. We solved the crystal structures of both the wild-type and chalcone-producing I207L/L208F mutant of Rheum palmatum BAS at 1.8 A resolution. In addition, we solved the crystal structure of the wild-type enzyme, in which a monoketide coumarate intermediate is covalently bound to the catalytic cysteine residue, at 1.6 A resolution. This is the first direct evidence that type III PKS utilizes the cysteine as the nucleophile and as the attachment site for the polyketide intermediate. The crystal structures revealed that BAS utilizes an alternative, novel active-site pocket for locking the aromatic moiety of the coumarate, instead of the chalcone synthase's coumaroyl-binding pocket, which is lost in the active-site of the wild-type enzyme and restored in the I207L/L208F mutant. Furthermore, the crystal structures indicated the presence of a putative nucleophilic water molecule which forms hydrogen bond networks with the Cys-His-Asn catalytic triad. This suggested that BAS employs novel catalytic machinery for the thioester bond cleavage of the enzyme-bound diketide intermediate and the final decarboxylation reaction to produce benzalacetone. These findings provided a structural basis for the functional diversity of the type III PKS enzymes.

PubMed: 20080733
DOI: 10.1073/pnas.0909982107

実験手法

X-RAY DIFFRACTION (1.8 Å)