Impact of SliP4 deletion on the high-light acclimation in Synechocystis sp. PCC 6803

PCC 6803 is exposed to high-light conditions. Deletion mutants of the sliP4 gene manifest a light-sensitive phenotype due to impaired cyclic electron flow and state transitions.

In this study, we aimed to investigate the consequences of SliP4 deficiency on the process of high-light acclimation. The sliP4 deletion mutant demonstrated a complete gene regulatory response 30 minutes after the light intensity was increased from 50 to 250 μmol photons m-2 s-1, a process that was mediated by the RpaB-PsrR1 system. However, after the shift to high light, the mutant increased the production of extracellular polysaccharides and the cells began to aggregate, thereby effectively reducing the potential impact of light stress effects caused by the impaired capacity for cyclic electron flow and state transitions.