7VEE

The ligand-free structure of GfsA KSQ-AT didomain

7VEE の概要

• エントリーDOI: 10.2210/pdb7vee/pdb
• 分子名称: Polyketide synthase, GLYCEROL (3 entities in total)
• 機能のキーワード: decarboxylase, thiolase fold, polyketide biosynthesis, biosynthetic protein, transferase
• 由来する生物種: Streptomyces graminofaciens
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 95624.70

構造登録者

Chisuga, T.,Miyanaga, A.,Nagai, A.,Kudo, F.,Eguchi, T. (登録日: 2021-09-08, 公開日: 2022-01-12, 最終更新日: 2023-11-29)

主引用文献

Chisuga, T.,Nagai, A.,Miyanaga, A.,Goto, E.,Kishikawa, K.,Kudo, F.,Eguchi, T.
Structural Insight into the Reaction Mechanism of Ketosynthase-Like Decarboxylase in a Loading Module of Modular Polyketide Synthases.
Acs Chem.Biol., 17:198-206, 2022

PubMed Abstract: Ketosynthase-like decarboxylase (KS) domains are widely distributed in the loading modules of modular polyketide synthases (PKSs) and are proposed to catalyze the decarboxylation of a malonyl or methylmalonyl unit for the construction of the PKS starter unit. KS domains have high sequence similarity to ketosynthase (KS) domains, which catalyze transacylation and decarboxylative condensation in polyketide and fatty acid biosynthesis, except that the catalytic Cys residue of KS domains is replaced by Gln in KS domains. Here, we present biochemical analyses of GfsA KS and CmiP4 KS, which are involved in the biosynthesis of FD-891 and cremimycin, respectively. analysis showed that these KS domains catalyze the decarboxylation of malonyl and methylmalonyl units. Furthermore, we determined the crystal structure of GfsA KS in complex with a malonyl thioester substrate analogue, which enabled identification of key amino acid residues involved in the decarboxylation reaction. The importance of these residues was confirmed by mutational analysis. On the basis of these findings, we propose a mechanism of the decarboxylation reaction catalyzed by GfsA KS. GfsA KS initiates decarboxylation by fixing the substrate in a suitable conformation for decarboxylation. The formation of enolate upon decarboxylation is assisted by two conserved threonine residues. Comparison of the structure of GfsA KS with those of KS domains suggests that the Gln residue in the active site of the KS domain mimics the acylated Cys residue in the active site of KS domains.

PubMed: 34985877
DOI: 10.1021/acschembio.1c00856

実験手法

X-RAY DIFFRACTION (2.55 Å)