title: Butanol tolerance regulated by a two-component response regulator Slr1037 in photosynthetic Synechocystis sp. PCC 6803.
abstract: BACKGROUND
  Butanol production directly from CO2 in photosynthetic cyanobacteria is restricted by the high toxicity of butanol to the hosts. In previous studies, we have found that a few two-component signal transduction systems (TCSTSs) were differentially regulated in Synechocystis sp. PCC 6803 after butanol treatment.
  
  
  RESULTS
  To explore regulatory mechanisms of butanol tolerance, in this work, by constructing gene knockout mutants of the butanol-responsive TCSTS genes and conducting tolerance analysis, we uncovered that an orphan slr1037 gene encoding a novel response regulator was involved in butanol tolerance in Synechocystis. Interestingly, the ∆slr1037 mutant grew similarly to the wild type under several other stress conditions tested, which suggests that its regulation on butanol tolerance is specific. Using a quantitative iTRAQ LC-MS/MS proteomics approach coupled with real-time reverse transcription PCR, we further determined the possible butanol-tolerance regulon regulated by Slr1037. The results showed that, after slr1037 deletion, proteins involved in photosynthesis and glycolysis/gluconeogenesis of central metabolic processes, and glutaredoxin, peptide methionine sulfoxide reductase and glucosylglycerol-phosphate synthase with stress-responsive functions were down-regulated, suggesting that Slr1037 may exhibit regulation to a wide range of cellular functions in combating butanol stress.
  
  
  CONCLUSIONS
  The study provided a proteomic description of the putative butanol-tolerance regulon regulated by the slr1037 gene. As the first signal transduction protein identified directly related to butanol tolerance, response regulator Slr1037 could be a natural candidate for transcriptional engineering to improve butanol tolerance in Synechocystis.
authors.affiliation: Laboratory of Synthetic Microbiology, School of Chemical Engineering & Technology, Tianjin University, Tianjin 300072, P.R. China ; Key Laboratory of Systems Bioengineering, Ministry of Education of China, Tianjin 300072, P.R. China ; Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, P.R. China.
authors.forename: Lei
authors.initials: L
authors.lastname: Chen
authors.affiliation: Laboratory of Synthetic Microbiology, School of Chemical Engineering & Technology, Tianjin University, Tianjin 300072, P.R. China ; Key Laboratory of Systems Bioengineering, Ministry of Education of China, Tianjin 300072, P.R. China ; Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, P.R. China.
authors.forename: Lina
authors.initials: L
authors.lastname: Wu
authors.affiliation: Laboratory of Synthetic Microbiology, School of Chemical Engineering & Technology, Tianjin University, Tianjin 300072, P.R. China ; Key Laboratory of Systems Bioengineering, Ministry of Education of China, Tianjin 300072, P.R. China ; Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, P.R. China.
authors.forename: Jiangxin
authors.initials: J
authors.lastname: Wang
authors.affiliation: Laboratory of Synthetic Microbiology, School of Chemical Engineering & Technology, Tianjin University, Tianjin 300072, P.R. China ; Key Laboratory of Systems Bioengineering, Ministry of Education of China, Tianjin 300072, P.R. China ; Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, P.R. China.
authors.forename: Weiwen
authors.initials: W
authors.lastname: Zhang
keywords: Butanol; Proteomics; Response regulator; Synechocystis; Tolerance