title: Serine/threonine protein kinase SpkG is a candidate for high salt resistance in the unicellular cyanobacterium Synechocystis sp. PCC 6803.
abstract: BACKGROUND
  Seven serine/threonine kinase genes have been predicted in unicellular cyanobacterium Synechocystis sp. PCC6803. SpkA and SpkB were shown to be required for cell motility and SpkE has no kinase activity. There is no report whether the other four STKs are involved in stress-mediated signaling in Synechocystis PCC6803.
  
  
  RESULTS
  In this paper, we examined differential expression of the other four serine/threonine kinases, SpkC, SpkD, SpkF and SpkG, at seven different stress conditions. The transcriptional level was up-regulated of spkG and down-regulated of spkC under high salt stress condition. Two spk deletion mutants, ΔspkC and ΔspkG, were constructed and their growth characteristic were examined compared to the wild strain. The wild strain and ΔspkC mutant were not affected under high salt stress conditions. In contrast, growth of spkG mutant was completely impaired. To further confirm the function of spkG, we also examined the effect of mutation of spkG on the expression of salt stress-inducible genes. We compared genome-wide patterns of transcription between wild-type Synechocystis sp. PCC6803 and cells with a mutation in the SpkG with DNA microarray analysis.
  
  
  CONCLUSIONS
  In this study, we first study the spkG gene as sensor of high salt signal. We consider that SpkG play essential roles in Synechocystis sp. for sensing the high salt signal directly, rather than mediating signals among other kinases. Our microarray experiment may help select relatively significant genes for further research on mechanisms of signal transduction of Synechocystis sp. PCC6803 under high salt stress.
authors.affiliation: Qingdao University of Science and Technology, Qingdao, China.
authors.forename: Chengwei
authors.initials: C
authors.lastname: Liang
authors.forename: Xiaowen
authors.initials: X
authors.lastname: Zhang
authors.forename: Xiaoyuan
authors.initials: X
authors.lastname: Chi
authors.forename: Xiangyu
authors.initials: X
authors.lastname: Guan
authors.forename: Youxun
authors.initials: Y
authors.lastname: Li
authors.forename: Song
authors.initials: S
authors.lastname: Qin
authors.forename: Hong Bo
authors.initials: HB
authors.lastname: Shao
mesh_terms: D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D005798:Genes, Bacterial / Q000235:genetics; D016254:Mutagenesis, Insertional / Q000187:drug effects / Q000235:genetics; D009154:Mutation / Q000235:genetics; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012965:Sodium Chloride / Q000494:pharmacology*; D013312:Stress, Physiological / Q000187:drug effects / Q000235:genetics; D046939:Synechocystis / Q000187:drug effects* / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D012097:Repressor Proteins; D012965:Sodium Chloride; D017346:Protein Serine-Threonine Kinases