pkn22 (alr2502) encoding a putative Ser/Thr kinase in the cyanobacterium Anabaena sp. PCC 7120 is induced by both iron starvation and oxidative stress and regulates the expression of isiA.
In cyanobacteria, the isiA gene is required for cell adaptation to oxidative damage caused by the absence of iron. We show here that a putative Ser/Thr kinase gene, pkn22 (alr2052), is activated by iron deficiency and oxidative damage in Anabaena sp. PCC 7120. A pkn22 insertion mutant is unable to grow when iron is limiting. pkn22 regulates the expression of isiA (encoding CP43'), but not of isiB (encoding flavodoxin) and psbC (CP43). Fluorescence measurement at 77 K reveals the absence of the typical signature of CP43' associated with photosystem I in the mutant under iron-limiting conditions. We propose that Pkn22 is required for the function of isiA/CP43' and constitutes a regulatory element necessary for stress response.
Xu
Wen-Liang
WL
Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, PR China.
Jeanjean
Robert
R
Liu
Yong-Ding
YD
Zhang
Cheng-Cai
CC
D017033:Anabaena / Q000201:enzymology* / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics*; D002352:Carrier Proteins / Q000235:genetics*; D004790:Enzyme Induction; D005418:Flavodoxin / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D007501:Iron / Q000494:pharmacology; D000090463:Iron Deficiencies; D045342:Light-Harvesting Protein Complexes; D009154:Mutation; D018384:Oxidative Stress; D010641:Phenotype; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics*; D017346:Protein Serine-Threonine Kinases / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects
D001426:Bacterial Proteins; D002352:Carrier Proteins; D005418:Flavodoxin; D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D012333:RNA, Messenger; C076726:chlorophyll A binding protein CP43, Cyanobacteria; D007501:Iron; D017346:Protein Serine-Threonine Kinases