Pyrrolysine, a novel genetically encoded amino acid

描述（由申请人提供）：pyrlysine是一种新型氨基酸，最近在微生物基因中被发现由UAG密码子编码，用于甲胺代谢。这是继硒半胱氨酸（18年前被发现是由微生物中的UGA密码子编码的）以来，第二个遗传编码非规范氨基酸的例子。硒型半胱氨酸广泛分布，是人体内硒的主要形式。根据这一先例，吡咯赖氨酸具有更广泛分布和在代谢中重要的潜力。无论如何，pyrlysine将作为生物体如何调节其遗传密码以扩大代谢能力的罕见例子，这一成就的复制为人工定制具有生物医学潜力的新蛋白质提供了希望。我们的长期目标是了解pyrlysine的功能，生物发生和遗传编码。假设UAG密码子的翻译需要一个专门的UAG解码tRNA和一个专门的同源氨基酰基-tRNA合成酶。这些基因产物和其他被认为参与UAG解码的基因产物如pyrlysine的作用将通过生化和遗传方法进行研究。pyrlysine的最终结构尚不清楚，通过分析蛋白质、细胞质和tRNA上的UAG编码残基，可以深入了解pyrlysine的结构和遗传编码。已经开发了一个体内系统，将用于研究UAG在翻译为pyrlysine期间如何作为一个意义而不是一个停止密码子起作用。一个类似的系统将用于定点诱变，以测试热裂解氨酸在酶催化中的假设功能。最后，转座子诱变将用于鉴定在UAG翻译过程中具有预期或未预期功能的未知基因，如pyrlysine。

DESCRIPTION (provided by applicant): Pyrrolysine, a novel amino acid, was recently found to be encoded by UAG codons in a microbial gene for methylamine metabolism. This is the second example of a genetically encoded non-canonical amino acid since selenocysteine, which 18 years ago was found to be encoded by UGA codons in a microbe. Selenocysteine is now known to be widely distributed and the primary form of selenium in humans. Following this precedent, pyrrolysine holds potential of being more widely distributed and of import in metabolism. Regardless, pyrrolysine will serve as a rare example of how organisms can modulate their genetic code to expand metabolic capabilities, an achievement whose replication holds promise for artificially tailoring novel proteins with biomedical potential. Our long-range goals are to understand the function, biogenesis, and genetic encoding of pyrrolysine. Translation of UAG codons is hypothesized to require a specialized UAG decoding tRNA and a dedicated cognate aminoacyl-tRNA synthetase. The roles of these gene products and others thought to be involved in UAG decoding as pyrrolysine will be investigated using biochemical and genetic approaches. The final structure of pyrrolysine is as yet unknown, and insight into pyrrolysine structure and genetic encoding will be gained by analyzing the UAG encoded residue in protein, the cytosol, and on tRNA. An in vivo system has been developed that will be used to study how UAG functions as a sense rather than a stop codon during UAG translation as pyrrolysine. A similar system will be used for site directed mutagenesis in order to test the hypothesized function of pyrrolysine in enzyme catalysis. Finally, transposon mutagenesis will be used to identify unknown genes with anticipated or unanticipated functions during UAG translation as pyrrolysine.