Web-Based Base Editing Toolkits: BE-Designer and BE-Analyzer.

The CRISPR-Cas system is broadly used for genome editing because of its convenience and relatively low cost. However, the use of CRISPR nucleases to induce specific nucleotide changes in target DNA requires complex procedures and additional donor DNAs. Furthermore, CRISPR nuclease-mediated DNA cleavage at target sites frequently causes large deletions or genomic rearrangements. In contrast, base editors that consist of catalytically dead Cas9 (dCas9) or Cas9 nickase (nCas9) connected to a cytidine or a guanine deaminase can correct point mutations in the absence of additional donor DNA and without generating double-strand breaks (DSBs) in the target region. To design target sites and assess mutation ratios for cytosine and adenine base editors (CBEs and ABEs), we have developed web tools, named BE-Designer and BE-Analyzer. These tools are easy to use (such that tasks are accomplished by clicking on relevant buttons) and do not require a deep knowledge of bioinformatics.