Scorer C A, Carrier M J, Rosenberger R F
Genetics Division, National Institute for Medical Research, London, UK.
Nucleic Acids Res. 1991 Jul 11;19(13):3511-6. doi: 10.1093/nar/19.13.3511.
To determine whether the high-level expression of foreign proteins in Escherichia coli can lead to frequent translational errors, we analyzed amino acid misincorporation in mouse epidermal growth factor (mEGF) produced as a TrpE fusion protein. The mEGF DNA does not encode phenylalanine and determining the phenylalanine content of the purified protein will measure missense errors. Using this approach, we found an error frequency of about 1 in 40 for codons differing by a single base from those for phenylalanine. This is at least ten times higher than the error rate found for normal E. coli protein synthesis and may be due to limiting supply of charged tRNAs and GTP, brought about by the high-level production of the heterologous protein. The unexpectedly high error rate has implications for the clinical use of E. coli-derived therapeutic proteins.
为了确定外源蛋白在大肠杆菌中的高水平表达是否会导致频繁的翻译错误，我们分析了作为TrpE融合蛋白产生的小鼠表皮生长因子（mEGF）中的氨基酸错掺入情况。mEGF DNA不编码苯丙氨酸，测定纯化蛋白中的苯丙氨酸含量将衡量错义错误。使用这种方法，我们发现与苯丙氨酸密码子相差一个碱基的密码子的错误频率约为四十分之一。这至少比正常大肠杆菌蛋白质合成中发现的错误率高十倍，可能是由于异源蛋白的高水平产生导致带电tRNA和GTP的供应受限。这一意外高的错误率对大肠杆菌来源的治疗性蛋白的临床应用具有重要意义。
