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Evolving a Thermostable Terminal Deoxynucleotidyl Transferase.
ACS Synthetic Biology ( IF 3.7 ) Pub Date : 2020-06-04 , DOI: 10.1021/acssynbio.0c00078
Jasmine Puay Suan Chua 1, 2, 3 , Maybelle Kho Go 1, 2 , Trina Osothprarop 4 , Seth Mcdonald 4 , Alexander G Karabadzhak 4 , Wen Shan Yew 1, 2 , Sergio Peisajovich 4 , Saurabh Nirantar 3
Affiliation  

Terminal deoxynucleotidyl transferase (TdT) catalyzes template free incorporation of arbitrary nucleotides onto single-stranded DNA. Due to this unique feature, TdT is widely used in biotechnology and clinical applications. One particularly tantalizing use is the synthesis of long de novo DNA molecules by TdT-mediated iterative incorporation of a 3′ reversibly blocked nucleotide, followed by deblocking. However, wild-type (WT) TdT is not optimized for the incorporation of 3′ modified nucleotides, and TdT engineering is hampered by the fact that TdT is marginally stable and only present in mesophilic organisms. We sought to first evolve a thermostable TdT variant to serve as backbone for subsequent evolution to enable efficient incorporation of 3′-modified nucleotides. A thermostable variant would be a good starting point for such an effort, as evolution to incorporate bulky modified nucleotides generally results in lowered stability. In addition, a thermostable TdT would also be useful when blunt dsDNA is a substrate as higher temperature could be used to melt dsDNA. Here, we developed an assay to identify thermostable TdT variants. After screening about 10 000 TdT mutants, we identified a variant, named TdT3-2, that is 10 °C more thermostable than WT TdT, while preserving the catalytic properties of the WT enzyme.

中文翻译:

不断发展的热稳定末端脱氧核苷酸转移酶。

末端脱氧核苷酸转移酶(TdT)催化将任意核苷酸无模板地整合到单链DNA上。由于这种独特的功能,TdT被广泛应用于生物技术和临床应用中。一种特别诱人的用途是Long de novo的合成DNA分子通过TdT介导的3'可逆封闭核苷酸的迭代掺入,然后解封闭。但是,野生型(WT)TdT并未针对3'修饰核苷酸的掺入进行优化,并且TdT处于边际稳定状态且仅存在于嗜温生物中这一事实阻碍了TdT工程化。我们试图首先进化热稳定的TdT变体,以用作后续进化的骨架,以使3'-修饰的核苷酸能够有效掺入。热稳定的变体将是这种努力的良好起点,因为掺入大体积修饰核苷酸的进化通常导致稳定性降低。另外,当钝的dsDNA是底物时,热稳定的TdT也将是有用的,因为可以使用更高的温度来熔化dsDNA。这里,我们开发了一种测定方法来鉴定热稳定的TdT变体。在筛选了大约10000个TdT突变体后,我们鉴定出一个名为TdT3-2的变体,该变体比WT TdT热稳定10°C,同时保留了WT酶的催化特性。
更新日期:2020-07-17
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