Structural Insights into the Free-Standing Condensation Enzyme SgcC5 Catalyzing Ester-Bond Formation in the Biosynthesis of the Enediyne Antitumor Antibiotic C-1027

Chin-Yuan Chang, Jeremy R. Lohman, Tingting Huang, Karolina Michalska, Lance Bigelow, Jeffrey D. Rudolf, Robert Jedrzejczak, Xiaohui Yan, Ming Ma, Gyorgy Babnigg, Andrzej Joachimiak, George N. Phillips, Ben Shen*

*此作品的通信作者

研究成果: Article同行評審

7 引文 斯高帕斯(Scopus)

摘要

C-1027 is a chromoprotein enediyne antitumor antibiotic, consisting of the CagA apoprotein and the C-1027 chromophore. The C-1027 chromophore features a nine-membered enediyne core appended with three peripheral moieties, including an (S)-3-chloro-5-hydroxy-β-tyrosine. In a convergent biosynthesis of the C-1027 chromophore, the (S)-3-chloro-5-hydroxy-β-tyrosine moiety is appended to the enediyne core by the free-standing condensation enzyme SgcC5. Unlike canonical condensation domains from the modular nonribosomal peptide synthetases that catalyze amide-bond formation, SgcC5 catalyzes ester-bond formation, as demonstrated in vitro, between SgcC2-tethered (S)-3-chloro-5-hydroxy-β-tyrosine and (R)-1-phenyl-1,2-ethanediol, a mimic of the enediyne core as an acceptor substrate. Here, we report that (i) genes encoding SgcC5 homologues are widespread among both experimentally confirmed and bioinformatically predicted enediyne biosynthetic gene clusters, forming a new clade of condensation enzymes, (ii) SgcC5 shares a similar overall structure with the canonical condensation domains but forms a homodimer in solution, the active site of which is located in a cavity rather than a tunnel typically seen in condensation domains, and (iii) the catalytic histidine of SgcC5 activates the 2-hydroxyl group, while a hydrogen-bond network in SgcC5 prefers the R-enantiomer of the acceptor substrate, accounting for the regio- and stereospecific ester-bond formation between SgcC2-tethered (S)-3-chloro-5-hydroxy-β-tyrosine and (R)-1-phenyl-1,2-ethanediol upon acid-base catalysis. These findings expand the catalytic repertoire and reveal new insights into the structure and mechanism of condensation enzymes.

原文English
頁(從 - 到)3278-3288
頁數11
期刊Biochemistry
57
發行號23
DOIs
出版狀態Published - 12 6月 2018

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