Incorporation of Fluorescent-Labeled Non-α-Amino Carboxylic Acids into the N-Terminus of Proteins in Response to Amber Initiation Codon
作者:Masanori Miura、Norihito Muranaka、Ryoji Abe、Takahiro Hohsaka
DOI:10.1246/bcsj.20090320
日期:2010.5.15
Incorporation of non-natural amino acid derivatives containing fluorescent groups into proteins is a useful method for protein analyses. Here, we investigated the incorporation of fluorescent-labeled non-α-amino carboxylic acids into the N-terminus of proteins in response to the UAG initiation codon. A series of TAMRA-labeled amino carboxylic acids were synthesized and attached to an amber suppressor initiator tRNA derived from Escherichia coli initiator tRNA. Fluorescent-labeled amino carboxylic acids were successfully incorporated into the N-terminus of streptavidin by adding TAMRA-acylated initiator tRNAs to an E. coli cell-free translation system, although the incorporation efficiency differed depending on the amino carboxylic acid chain length. Based on this observation, 3-aminopropionic acid derivatives labeled with BODIPY, rhodamine, and cyanine fluorophores were designed and synthesized. The fluorescent-labeled 3-aminopropionic acid derivatives developed using BODIPY and rhodamine dyes could be incorporated with good efficiency. On the other hand, 6-aminohexanoic acid was effectively incorporated when labeled with cyanine dyes. The present study demonstrates that translation initiation can accept a wide variety of non-natural substrates and provides a useful method for N-terminal-specific labeling of proteins with various fluorophores.
将含荧光基团的非天然氨基酸衍生物掺入蛋白质中是一种有用的蛋白质分析方法。在此,我们研究了在UAG起始密码子的响应下,将荧光标记的非α-氨基酸羧酸掺入蛋白质N末端的过程。合成了一系列TAMRA标记的氨基酸羧酸,并将其连接到由大肠杆菌起始tRNA衍生的琥珀抑制起始tRNA上。通过向大肠杆菌无细胞翻译系统中添加TAMRA酰化的起始tRNA,成功地将荧光标记的氨基酸羧酸掺入链霉亲和素的N末端,尽管掺入效率因氨基酸羧酸链长而异。基于这一观察,设计并合成了使用BODIPY、罗丹明和花菁荧光染料标记的3-氨基丙酸衍生物。使用BODIPY和罗丹明染料开发的荧光标记3-氨基丙酸衍生物可以高效掺入。另一方面,当使用花菁染料标记时,6-氨基己酸可以有效掺入。本研究表明,翻译起始可以接受各种非天然底物,并提供了一种有用的方法,用于使用各种荧光团对蛋白质N末端进行特异性标记。