Investigation of singlet‐oxygen‐responsive genes in the cyanobacterium Synechocystis PCC 6803

Patyi, Gábor and Hódi, Barbara and Mallick, Ivy and Maróti, Gergely and Kós, Péter and Vass, Imre (2024) Investigation of singlet‐oxygen‐responsive genes in the cyanobacterium Synechocystis PCC 6803. PHYSIOLOGIA PLANTARUM, 176 (4). pp. 1-20. ISSN 0031-9317

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Abstract

Singlet oxygen ( 1 O 2 ) is an important reactive oxygen species whose formation by the type‐II, light‐dependent, photodynamic reaction is inevitable during photosynthetic processes. In the last decades, the recognition that 1 O 2 is not only a damaging agent, but can also affect gene expression and participates in signal transduction pathways has received increasing attention. However, contrary to several other taxa, 1 O 2 ‐responsive genes have not been identified in the important cyanobacterial model organism Synechocystis PCC 6803. By using global transcript analysis we have identified a large set of Synechocystis genes, whose transcript levels were either enhanced or repressed in the presence of 1 O 2 . Characteristic 1 O 2 responses were observed in several light‐inducible genes of Synechocystis , especially in the hli (or scp ) family encoding HLIP/SCP proteins involved in photoprotection. Other important 1 O 2 ‐induced genes include components of the Photosystem II repair machinery ( psbA2 and ftsH2 , ftsH3 ), iron homeostasis genes isiA and idiA , the group 2 sigma factor sig D, some components of the transcriptomes induced by salt‐, hyperosmotic and cold‐stress, as well as several genes of unknown function. The most pronounced 1 O 2 ‐induced upregulation was observed for the hliB and the co‐transcribed lilA genes, whose deletion induced enhanced sensitivity against 1 O 2 ‐mediated light damage. A bioreporter Synechocystis strain was created by fusing the hliB promoter to the bacterial luciferase (lux), which showed its utility for continuous monitoring of 1 O 2 concentrations inside the cell.

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