GROWTH-RATE DEPENDENCE OF TRANSFER-RNA ABUNDANCE IN ESCHERICHIA-COLI
GROWTH-RATE DEPENDENCE OF TRANSFER-RNA ABUNDANCE IN ESCHERICHIA-COLI
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DOI：
10.1002/j.1460-2075.1990.tb07885.x
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发表时间：
1990-12-01
期刊：
影响因子：
11.4
通讯作者：
KURLAND, CG
中科院分区：
文献类型：
--
作者：
EMILSSON, V;KURLAND, CG
我们已经测试了一个模型的预测，该模型解释了细菌在生长最大化策略方面的密码子偏好。根据该模型，在不同的生长条件下，与次要密码子同源的tRNA种类应受到不同的调控：与主要密码子同源的同受体应以快速增长的速度增加，而与次要密码子同源的同受体应以快速增长的速度减少。我们使用了定量的Northern印迹技术来测量蛋氨酸和亮氨酸等受体家族在每小时0.5到2.1倍的生长速率下的丰度。与次要密码子同源的5种tRNA（tRNA(e)Met、tRNA1fMet、tRNA2fMet、tRNA1Leu和tRNA3Leu）在总tRNA中所占的相对比例和绝对浓度均随着生长速率的增加而增加。tRNA2Lue、tRNA4Leu和tRNA5Leu是三种与小孔菌同源的tRNA物种，它们占总RNA的相对比例和绝对浓度随着生长速率的增加而降低。这些数据表明，tRNA物种群的丰度以不同的方式调节，并且它们不是简单地根据同受体特异性调节的。特别是，这些数据支持密码子偏倚的生长优化模型。
We have tested the predictions of a model that accounts for the codon preferences of bacteria in terms of a growth maximization strategy. According to this model the tRNA species cognate to minor and major condons should be regulated differently under different growth conditions: the isoacceptors cognate to major codons should increase at fast growth rates while those cognate to minor codons should decrease at fast growth rates. We have used a quantitative Northern blotting technique to measure the abundance of the methionine and the luecine isoacceptor families over growth rates ranging from 0.5 to 2.1 doublings per hour. Five tRNA species that are cognate to minor codons (tRNA(e)Met, tRNA1fMet, tRNA2fMet, tRNA1Leu and tRNA3Leu) increase both as a relative fraction of total tRNA and in absolute concentration with increasing growth rates. Three tRNA species that are cognate to minor condons (tRNA2Lue, tRNA4Leu and tRNA5Leu) decrease as a relative fraction of total RNA and in absolute concentration with increasing growth rates. These data suggest that the abundances of groups of tRNA species are regulated in different ways, and that they are not regulated simply according to isoacceptor specificity. In particular, the data support the growth optimization model for codon bias.