Post-transcriptional autoregulation of gene expression is common in bacterial systems but many fewer examples are known in eukaryotes. We used the yeast collection of genes fused to GFP as a rapid screen for examples of feedback regulation in ribosomal proteins by overexpressing a non-regulatable version of a gene and observing the effects on the expression of the GFP-fused version. We tested 95 ribosomal protein genes and found that 21 of them showed at least a three-fold repression. Two genes, RPS22B and RPL1B, showed over a 10-fold repression. In both cases the cis-regulatory segment resides in the 5’ UTR of the gene as shown by placing that segment of the mRNA upstream of GFP alone and demonstrating it is sufficient to cause repression of GFP when the protein is over-expressed. Further analyses showed that the intron in the 5’ UTR of RPS22B is required for regulation, presumably because the protein inhibits splicing that is necessary for translation. The 5’ UTR of RPL1B contains a sequence and structure motif that is conserved in the binding sites of Rpl1 orthologs from bacteria to mammals, and mutations within the motif eliminate repression.

中文翻译：

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通过有效搜索反馈调节发现的许多酵母核糖体蛋白的自动调节

基因表达的转录后自动调节在细菌系统中很常见，但在真核生物中已知的例子很少。我们使用酵母融合到GFP的基因的集合作为快速筛选，通过过表达基因的非调控形式并观察对GFP融合形式的表达的影响来核糖体蛋白中的反馈调节。我们测试了95个核糖体蛋白基因，发现其中的21个显示出至少三倍的抑制。RPS22B和RPL1B两个基因，显示超过10倍的压抑。在这两种情况下，顺式调节片段都位于基因的5'UTR中，这是通过将mRNA的该片段单独置于GFP的上游来证明的，并证明了当蛋白过表达时，它足以引起GFP的阻遏。进一步的分析表明，RPS22B的5'UTR中的内含子是调控所必需的，大概是因为该蛋白质抑制了翻译所必需的剪接。RPL1B的5'UTR包含一个序列和结构基序，该基序在从细菌到哺乳动物的Rpl1直向同源物的结合位点中保守，并且基序内的突变消除了抑制。