Unexpected Preference of the E. coli Translation System for the Ester Bond during Incorporation of Backbone-Elongated Substrates

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• 作者：Shinsuke Sando ; Kenji Abe ; Nobuhiko Sato ; Toshihiro Shibata ; Keigo Mizusawa ; Yasuhiro Aoyama
• 刊名：Journal of the American Chemical Society
• 出版年：2007
• 出版时间：May 16, 2007
• 年：2007
• 卷：129
• 期：19
• 页码：6180 - 6186
• 全文大小：217K
• 年卷期：v.129,no.19(May 16, 2007)
• ISSN：1520-5126

文摘

There have been recent advances in the ribosomal synthesis of various molecules composedof nonnatural ribosomal substrates. However, the ribosome has strict limitations on substrates with elongatedbackbones. Here, we show an unexpected loophole in the E. coli translation system, based on a remarkabledisparity in its selectivity for -amino/hydroxy acids. We challenged -hydroxypropionic acid (-HPA), whichis less nucleophilic than -amino acids but free from protonation, to produce a new repertoire of ribosome-compatible but main-chain-elongated substrates. PAGE analysis and mass-coupled S-tag assays of ambersuppression experiments using yeast suppressor tRNA^Phe_CUA confirmed the actual incorporation of -HPAinto proteins/oligopeptides. We investigated the side-chain effects of -HPA and found that the side chainat position and R stereochemistry of the -substrate is preferred and even notably enhances the efficiencyof incorporation as compared to the parent substrate. These results indicate that the E. coli translationmachinery can utilize main-chain-elongated substrates if the pK_a of the substrate is appropriately chosen.