Selective transcription of individual protein coding genes does not occur in trypanosomes and the cellular copy number of each mRNA must be determined post-transcriptionally. Here, we provide evidence that codon choice directs the levels of constitutively expressed mRNAs. First, a novel codon usage metric, the gene expression codon adaptation index (geCAI), was developed that maximised the relationship between codon choice and the measured abundance for a transcriptome. Second, geCAI predictions of mRNA levels were tested using differently coded GFP transgenes and were successful over a 25-fold range, similar to the variation in endogenous mRNAs. Third, translation was necessary for the accelerated mRNA turnover resulting from codon choice. Thus, in trypanosomes, the information determining the levels of most mRNAs resides in the open reading frame and translation is required to access this information.

中文翻译：

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密码子选择指导锥虫中的组成型 mRNA 水平

锥虫中不会发生单个蛋白质编码基因的选择性转录，并且每个 mRNA 的细胞拷贝数必须在转录后确定。在这里，我们提供了密码子选择指导组成型表达 mRNA 水平的证据。首先，开发了一种新的密码子使用指标，即基因表达密码子适应指数（geCAI），它最大化了密码子选择和转录组测量丰度之间的关系。其次，使用不同编码的 GFP 转基因测试了 geCAI 对 mRNA 水平的预测，并在 25 倍范围内成功，类似于内源 mRNA 的变化。第三，翻译对于密码子选择导致的 mRNA 更新加速是必要的。因此，在锥虫中，决定大多数 mRNA 水平的信息位于开放阅读框中，需要翻译才能获取该信息。