GRATUITOUS OVEREXPRESSION OF GENES IN ESCHERICHIA-COLI LEADS TO GROWTH-INHIBITION AND RIBOSOME DESTRUCTION
GRATUITOUS OVEREXPRESSION OF GENES IN ESCHERICHIA-COLI LEADS TO GROWTH-INHIBITION AND RIBOSOME DESTRUCTION
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DOI：
10.1128/jb.177.6.1497-1504.1995
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发表时间：
1995-03-01
影响因子：
3.2
通讯作者：
KURLAND, CG
中科院分区：
文献类型：
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作者：
DONG, HJ;NILSSON, L;KURLAND, CG
我们尝试通过改变其同源密码子浓度来测试在大肠杆菌中每个单独的tRNA同工受体的相对丰度可以通过改变其同源密码子浓度来改变信使池的总体密码子组成。为了改变信使池的总体密码子组成，我们在E.coliLacZ中借助T7RNA聚合酶表达了一个截短的tufB基因(命名为Delta tufB)，使得它们各自的基因产物分别占细菌总蛋白的30%，出乎意料的是，这两个测试基因的最大表达对我们研究的tRNA物种的相对合成速率没有特定的影响。我们发现rRNAs的累积分解导致核糖体和蛋白质合成能力的丧失，在最大限度地诱导任一测试基因后，有越来越多的蛋白质合成投资于β-半乳糖苷酶或Delta tufB，与之匹配的是正常蛋白质合成的相对减少，我们还观察到两种热休克蛋白在过度表达过程中的增强积累，最后，在两种测试蛋白的过表达几个小时后，细菌不再具有生存能力。这些结果与获得高表达克隆蛋白的实际问题有关。
We attempted to test the idea that the relative abundance of each individual tRNA isoacceptor in Escherichia coli can be altered by varying its cognate codon concentration, In order to change the overall codon composition of the messenger pool, we have expressed in E. coli lacZ with the aid of T7 RNA polymerase and, separately, we have expressed a truncated tufB gene (designated Delta tufB) with the aid of E. coli RNA polymerase so that their respective gene products individually accounted for 30% of the total bacterial protein, Unexpectedly, the maximum expression of either test gene has no specific effect on the relative rates of synthesis of the tRNA species that we studied, Instead, we find that there is a cumulative breakdown of rRNAs, which results in a loss of ribosomes and protein synthetic capacity, After either of the test genes is maximally induced, there is a growing fraction of protein synthesis invested in beta-galactosidase or Delta tufB that is matched by a comparable decrease of the fraction of normal protein synthesis, We have also observed enhanced accumulation of two heat shock proteins during overexpression, Finally, after several hours of overexpression of either test protein, the bacteria are no longer viable. These results are relevant to the practical problems of obtaining high expression levels for cloned proteins.