The response regulator RpaB binds the high light regulatory 1 sequence upstream of the high-light-inducible hliB gene from the cyanobacterium Synechocystis PCC 6803.

Cyanobacteria, like other photosynthetic organisms, respond to the potentially damaging effects of high-intensity light by regulating the expression of a variety of stress-responsive genes through regulatory mechanisms that remain poorly understood. The high light regulatory 1 (HLR1) sequence can be found upstream of many genes regulated by high-light (HL) stress in cyanobacteria. In this study, we identify the factor that binds the HLR1 upstream of the HL-inducible hliB gene in the cyanobacterium Synechocystis PCC 6803 as the RpaB (Slr0947) response regulator.