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Completely Free from PAM Limitations: Asymmetric RPA with CRISPR/Cas12a for Nucleic Acid Assays
ACS Sensors ( IF 8.2 ) Pub Date : 2023-11-27 , DOI: 10.1021/acssensors.3c01686
Gaihua Cao 1, 2 , Nannan Yang 1, 2 , Yifan Xiong 1, 2 , Meimei Shi 2 , Lin Wang 3 , Fuping Nie 2 , Danqun Huo 1 , Changjun Hou 1, 4
Affiliation  

Experimentally, Cas12a can recognize multiple protospacer adjacent motif (PAM) sequences and is not restricted to the “TTTN”. However, the application of the CRISPR/Cas12a system is still limited by the PAM for double-stranded DNA (dsDNA). Here, we developed asymmetric RPA (Asy-RPA) to completely break the limitations of PAM. Asy-RPA not only achieved efficient amplification but also converted dsDNA to single-stranded DNA (ssDNA) without complicated steps. The ssDNA products activated the trans-cleavage activity of Cas12a, outputting signals. The application of Asy-RPA completely freed Cas12a from the PAM, which can be more widely used in nucleic acid detection, such as lumpy skin disease virus, with an actual detection limit as low as 1.21 × 101 copies·μL–1. More importantly, Cas12a was intolerant to mutations on ssDNA. This provided technical support for the detection and identification of wild-type Mycobacterium tuberculosis (WT-TB) and rifampin-resistant mutant-type M. tuberculosis (MT-TB). The detection limit was as low as 1 fM for 1% mixed samples. The detection and availability of different treatment options for treatment-resistant and WT-TB were significant for the elimination of TB. In summary, the platform consisting of Asy-RPA and CRISPR/Cas12a was suitable for the detection of various viruses and bacteria and was a boon for the detection of dsDNA without recognizable PAM.

中文翻译:


完全摆脱 PAM 限制:使用 CRISPR/Cas12a 进行核酸检测的不对称 RPA



实验上,Cas12a可以识别多个原型间隔子相邻基序(PAM)序列,并且不限于“TTTN”。然而,CRISPR/Cas12a系统的应用仍然受到双链DNA(dsDNA)PAM的限制。在这里,我们开发了非对称RPA(Asy-RPA)来彻底打破PAM的局限性。 Asy-RPA不仅实现了高效扩增,而且无需复杂的步骤即可将dsDNA转化为单链DNA(ssDNA)。 ssDNA产物激活Cas12a的反式切割活性,输出信号。 Asy-RPA的应用将Cas12a彻底从PAM中解放出来,可以更广泛地应用于核酸检测,如结节性皮肤病病毒,实际检测限低至1.21×10 1拷贝·μL –1 。更重要的是,Cas12a 不能耐受 ssDNA 突变。这为野生型结核分枝杆菌(WT-TB)和利福平耐药突变型结核分枝杆菌(MT-TB)的检测和鉴定提供了技术支持。 1% 混合样品的检测限低至 1 fM。针对耐药结核病和野生型结核病的不同治疗方案的检测和可用性对于消除结核病具有重要意义。综上所述,Asy-RPA和CRISPR/Cas12a组成的平台适用于多种病毒和细菌的检测,对于无法识别PAM的dsDNA检测来说是一个福音。
更新日期:2023-11-27
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