Photosynthetic electron transport controls expression of the high light inducible gene in the cyanobacterium Synechococcus elongatus strain PCC 7942

Abstract

The hliA gene of Synechococcus, encoding a photoprotective high light inducible polypeptide, is up-regulated by high light (HL) or low intensity blue/UV-A light (BL). hliA expression was found to be up-regulated by KCN in low light (LL) (but not in the dark), and up-regulation in HL, BL, and LL (with KCN) was inhibited by 2,5-dibromo-3-methyl-6-isopropyl-benzoquinone. A working hypothesis is proposed whereby up-regulation is in response to the reduced state of cytochrome b6f or a carrier beyond in photosynthesis. Modest up-regulation occurs in LL by treatment with 3-(3,4-dichlorophenyl)-1,1- dimethylurea, but this is related to effects on hliA mRNA stability rather than on transcription.