tRNA variant library screening

Contains paired plasmid DNA (pDNA) and circularized RNA (circRNA) reads from tRNA variant libraries in HEK293T cells with or without a CMV promoter present upstream of the library. pDNA reads contain 5' and 3' barcodes flanking a central tRNA variant. These barcodes allow assignment of circRNA reads which have been processed (and thus the read does not contain the tRNA) to a given variant. In the (-)CMV libraries, circRNA/pDNA ratio can be used as a measurement of promoter strength. 3’ processing can be measured as processed 3’ circRNA reads/total circRNA reads for a given variant in the (-)CMV condition. 5’ processing can be estimated as processed 5’ circRNA reads/total circRNA reads in the (+)CMV condition. Barcodes have been partially degraded in the (+)CMV case (likely as a result of the decapping reaction necessary for circularizing Pol-II transcripts), and thus assignment of tRNA variants in this instance must be done using a partial barcode.