5KBZ

Structure of the PksA Product Template domain in complex with a phosphopantetheine mimetic

5KBZ の概要

• エントリーDOI: 10.2210/pdb5kbz/pdb
• 関連するPDBエントリー: 3hrr
• 分子名称: Noranthrone synthase, (14R)-14-hydroxy-15,15-dimethyl-1-[5-({[(5-methyl-1,2-oxazol-3-yl)methyl]sulfanyl}methyl)-1,2-oxazol-3-yl]-4,9,13-trioxo-2-thia-5,8,12-triazahexadecan-16-yl dihydrogen phosphate (3 entities in total)
• 機能のキーワード: aflatoxin, polyketide synthase, polyketide, product template, dehydratase, double hot dog fold, cyclase, transcription
• 由来する生物種: Aspergillus parasiticus
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 84367.51

構造登録者

Tsai, S.C.,Burkart, M.D.,Townsend, C.A.,Barajas, J.F.,Shakya, G.,Topper, C.L.,Moreno, G.,Jackson, D.R.,Rivera, H.,La Clair, J.J.,Vagstad, A. (登録日: 2016-06-03, 公開日: 2017-05-10, 最終更新日: 2023-09-27)

主引用文献

Barajas, J.F.,Shakya, G.,Moreno, G.,Rivera, H.,Jackson, D.R.,Topper, C.L.,Vagstad, A.L.,La Clair, J.J.,Townsend, C.A.,Burkart, M.D.,Tsai, S.C.
Polyketide mimetics yield structural and mechanistic insights into product template domain function in nonreducing polyketide synthases.
Proc. Natl. Acad. Sci. U.S.A., 114:E4142-E4148, 2017

PubMed Abstract: Product template (PT) domains from fungal nonreducing polyketide synthases (NR-PKSs) are responsible for controlling the aldol cyclizations of poly-β-ketone intermediates assembled during the catalytic cycle. Our ability to understand the high regioselective control that PT domains exert is hindered by the inaccessibility of intrinsically unstable poly-β-ketones for in vitro studies. We describe here the crystallographic application of "atom replacement" mimetics in which isoxazole rings linked by thioethers mimic the alternating sites of carbonyls in the poly-β-ketone intermediates. We report the 1.8-Å cocrystal structure of the PksA PT domain from aflatoxin biosynthesis with a heptaketide mimetic tethered to a stably modified 4'-phosphopantetheine, which provides important empirical evidence for a previously proposed mechanism of PT-catalyzed cyclization. Key observations support the proposed deprotonation at C4 of the nascent polyketide by the catalytic His1345 and the role of a protein-coordinated water network to selectively activate the C9 carbonyl for nucleophilic addition. The importance of the 4'-phosphate at the distal end of the pantetheine arm is demonstrated to both facilitate delivery of the heptaketide mimetic deep into the PT active site and anchor one end of this linear array to precisely meter C4 into close proximity to the catalytic His1345. Additional structural features, docking simulations, and mutational experiments characterize protein-substrate mimic interactions, which likely play roles in orienting and stabilizing interactions during the native multistep catalytic cycle. These findings afford a view of a polyketide "atom-replaced" mimetic in a NR-PKS active site that could prove general for other PKS domains.

PubMed: 28484029
DOI: 10.1073/pnas.1609001114

実験手法

X-RAY DIFFRACTION (1.803 Å)