Horizon’s Pin-point base editing technology utilizes an RNA aptamer embedded within the sgRNA to enable the recruitment of an effector module, e.g., cytidine deaminase. The resultant modularity enables a high degree of flexibility within the system which can be exploited to alter critical aspects of editing behavior including efficiency, window size and position, and nucleotide context preference.

In this study we report on the development of a base editing arrayed screening platform to assess and characterize the impact of different deaminases on the editing profile of the Pin-Point base editor system. The high-throughput nature of the screening platform that we have developed allows for the characterization of the base editor against a more comprehensive set of target loci, including previously un-tested guides. Here we demonstrate the utility of the screening platform in multiple cell lines, using five different cytidine deaminases and three structurally distinct tracrRNAs, and assess each configuration of the Pin-point system at seventy guide-specific genomic sites.

The robust data generated clearly show the utility of the base editor screening platform to characterize the resultant genomic editing profile obtained with each of the editor architectures generated within the Pin-Point system. In utilizing the arrayed screening platform, we demonstrate significant impact upon editing efficiency, editing window size, and context preference with different deaminases. Furthermore, we observe a major impact upon editing efficiency with different sgRNA/aptamer architectures. In summary we present the Pin-point platform as a tuneable, modular system whose functionality can be readily adapted to address diverse editing requirements. Further, the ability to comprehensively screen multiple iterations of Pin-point in a high-throughput manner promises to enable customization to meet unique researcher base editing requirements.