Fail-safe genetic codes designed to intrinsically contain engineered organisms
Fail-safe genetic codes designed to intrinsically contain engineered organisms
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DOI：
10.1093/nar/gkz745
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发表时间：
2019-11-04
影响因子：
14.9
通讯作者：
Endy, Drew
中科院分区：
文献类型：
--
作者：
Calles, Jonathan;Justice, Isaac;Endy, Drew
工程生物面临的一个挑战是对它们的行为负责。在使用前或使用期间发生的自发突变可能影响异源遗传功能，破坏系统整合或改变生物体表型。在这里，我们建议重组遗传密码本身，使蛋白质编码序列中的点突变被选择。如此编码的合成遗传系统在应对大多数自发突变时应该会更安全地失败。我们设计了故障安全代码，并模拟了它们对编码蛋白质进化的预期影响。我们预测支持20或15个氨基酸表达的故障安全代码可以将蛋白质进化速度分别减慢到标准编码蛋白质的30%或0%。我们还设计了四重密码子编码，以确保蛋白质编码序列中的所有单点突变都被选择，同时保持20个或更多个氨基酸的表达。我们的实验表明，一组减少的21个tRNA能够表达的蛋白质编码只有20个有义密码子，而标准的64密码子编码不表达。我们的工作表明，使用合理耗尽但其他自然翻译系统的生物系统应该进化得更慢，这种低进化的生物可能不太可能入侵新的生态位或超越本地种群。
One challenge in engineering organisms is taking responsibility for their behavior over many generations. Spontaneous mutations arising before or during use can impact heterologous genetic functions, disrupt system integration, or change organism phenotype. Here, we propose restructuring the genetic code itself such that point mutations in protein-coding sequences are selected against. Synthetic genetic systems so-encoded should fail more safely in response to most spontaneous mutations. We designed fail-safe codes and simulated their expected effects on the evolution of so-encoded proteins. We predict fail-safe codes supporting expression of 20 or 15 amino acids could slow protein evolution to similar to 30% or 0% the rate of standard-encoded proteins, respectively. We also designed quadruplet-codon codes that should ensure all single point mutations in protein-coding sequences are selected against while maintaining expression of 20 or more amino acids. We demonstrate experimentally that a reduced set of 21 tRNAs is capable of expressing a protein encoded by only 20 sense codons, whereas a standard 64-codon encoding is not expressed. Our work suggests that biological systems using rationally depleted but otherwise natural translation systems should evolve more slowly and that such hypoevolvable organisms may be less likely to invade new niches or outcompete native populations.