Ramírez-Prado Jorge Humberto, Martínez-Márquez Eva Isabel, Olmedo-Alvarez Gabriela
Departamento de Ingeniería Genética, Centro de Investigación y de Estudios Avanzados, Unidad Irapuato, México.
Curr Microbiol. 2006 Jul;53(1):23-9. doi: 10.1007/s00284-005-5178-1. Epub 2006 Jun 6.
We analyzed the influence of the 5' and 3' untranslated regions of the Bacillus thuringiensis cry1Aa on its mRNA stability. Although the cry1Aa gene has a stable transcript (8 min), its 5' UTR did not provide stability to the reporter gene uidA. Stability of cry1Aa could be increased to 40 min by addition of an SP82 stability element at the 5' UTR, suggesting that once the 5' and 3' ends were protected initiation of decay could be effectively blocked. We generated mutations in the transcription terminator and found that changes that reduced the stability of the stem, a larger loop, or elimination of the U-trail sharply decreased the half-life of the transcript. Therefore, unlike some stable bacterial transcripts, cry1Aa lacks special features at the end 5' to prevent decay, but its terminator is the main determinant of its stability.
我们分析了苏云金芽孢杆菌cry1Aa基因的5'和3'非翻译区对其mRNA稳定性的影响。尽管cry1Aa基因具有稳定的转录本（8分钟），但其5'非翻译区并未赋予报告基因uidA稳定性。通过在5'非翻译区添加SP82稳定元件，cry1Aa的稳定性可提高至40分钟，这表明一旦5'和3'末端得到保护，衰变起始就能被有效阻断。我们在转录终止子中产生了突变，发现降低茎的稳定性、增大环或去除U尾的变化会大幅缩短转录本的半衰期。因此，与一些稳定的细菌转录本不同，cry1Aa在5'末端缺乏防止衰变的特殊特征，但其终止子是其稳定性的主要决定因素。
