title: A novel transcriptional regulator, Sll1130, negatively regulates heat-responsive genes in Synechocystis sp. PCC6803.
abstract: 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.
authors.affiliation: Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad 500 046, India.
authors.forename: Pilla Sankara
authors.initials: PS
authors.lastname: Krishna
authors.forename: Balaga Radha
authors.initials: BR
authors.lastname: Rani
authors.forename: M Karthik
authors.initials: MK
authors.lastname: Mohan
authors.forename: Iwane
authors.initials: I
authors.lastname: Suzuki
authors.forename: Sisinthy
authors.initials: S
authors.lastname: Shivaji
authors.forename: Jogadhenu S S
authors.initials: JS
authors.lastname: Prakash
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D004269:DNA, Bacterial / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D006360:Heat-Shock Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D018869:Heat-Shock Response / Q000235:genetics / Q000502:physiology; D008954:Models, Biological; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D020411:Oligonucleotide Array Sequence Analysis; D020836:Protein Structure, Quaternary; D017386:Sequence Homology, Amino Acid; D046939:Synechocystis / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D006360:Heat-Shock Proteins; D014157:Transcription Factors