Kraljevic, M.; Ozturk, A.; Jank, M.; LeDuc, R. D.; Keijzer, R.

Circular RNAs (circRNAs) are generated through back-splicing, a process where a backsplice junction (BSJ) is formed, based on the circRNAs' unique sequence. BSJs are highly conserved and can be mapped to chromosomal coordinates. Current platforms determine these coordinates from bulk RNA sequencing data. We aimed to develop a tool capable of determining backsplice coordinates based on BSJ sequences for any species and genome version. Motivation: circRNAs are emerging as an important regulator of cellular differentiation and other biologically important processes. Common tools for circRNA analyses require a circular RNA's backsplice coordinates. These can be accessed from public databases. However, the coordinates are specific to a version of a species' genome, and are unavailable for many model organisms. Results: We have developed a Python-based, command line tool, FindBacksplice, which produces backsplice coordinates for any available genome, based on a circRNA's BSJ sequence. Implemented in Python, this script is integrated with BLAST for use in existing pipelines. We were able to find valid locations of backsplices for known human BSJs in the rat genome and produce backsplice coordinates for use in existing pipelines. Availability and implementation: FindBacksplice is available at github.com/m-kraljevic/findbacksplice