Lys-CRISPRi

A pooled CRISPRi libary with up to five sgRNAs targeting each annotated gene in Synechocystis sp. PCC 6803 was grown as described in Miao & Jahn et al., 2023 (https://doi.org/10.1093/plcell/koad208) in the presence or absence of 25 µM L-lysine. Sequencing samples to check for the abundance of different sgRNAs were taken before the addition of aTc and when the control library's growth reached the 8th generation. Comparison of the enrichment and depletion of different sgRNAs among the two conditions enabled us to identify genes whose repression gave a fitness advantage specifically when L-lysine was present.