A novel transcriptional regulator, Sll1130, negatively regulates heat-responsive genes in Synechocystis sp. PCC6803

Biochem J. 2013 Feb 1;449(3):751-60. doi: 10.1042/BJ20120928.


A conserved hypothetical protein, Sll1130, is a novel transcription factor that regulates the expression of major heat-responsive genes in Synechocystis sp. PCC6803. Synechocystis exhibited an increased thermotolerance due to disruption of sll1130. Δsll1130 cells recovered much faster than wild-type cells after they were subjected to heat shock (50°C) for 30 min followed by recovery at 34°C for 48 h. In Δsll1130 cultures, 70% of the cells were viable compared with the wild-type culture in which only 30% of the cells were viable. DNA microarray analysis revealed that in Δsll1130, expression of the heat-responsive genes such as htpG, hspA, isiA, isiB and several hypothetical genes were up-regulated. Sll1130 binds to a conserved inverted-repeat (GGCGATCGCC) located in the upstream region of the above genes. In addition, both the transcript and protein levels of sll1130 were immediately down-regulated upon shift of wild-type cells from 34 to 42°C. Collectively the results of the present study suggest that Sll1130 is a heat-responsive transcriptional regulator that represses the expression of certain heat-inducible genes at optimum growth temperatures. Upon heat shock, a quick drop in the Sll1130 levels leads to de-repression of the heat-shock genes and subsequent thermal acclimation. On the basis of the findings of the present study, we present a model which describes the heat-shock response involving Sll1130.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Base Sequence
  • DNA, Bacterial / genetics
  • Gene Expression Regulation, Bacterial
  • Genes, Bacterial
  • Heat-Shock Proteins / chemistry
  • Heat-Shock Proteins / genetics
  • Heat-Shock Proteins / metabolism
  • Heat-Shock Response / genetics
  • Heat-Shock Response / physiology
  • Models, Biological
  • Molecular Sequence Data
  • Mutagenesis, Insertional
  • Oligonucleotide Array Sequence Analysis
  • Protein Structure, Quaternary
  • Sequence Homology, Amino Acid
  • Synechocystis / genetics*
  • Synechocystis / metabolism
  • Transcription Factors / chemistry
  • Transcription Factors / genetics
  • Transcription Factors / metabolism
  • Up-Regulation


  • Bacterial Proteins
  • DNA, Bacterial
  • Heat-Shock Proteins
  • Transcription Factors