FisR activates σ54‐dependent transcription of sulfide‐oxidizing genes in Cupriavidus pinatubonensisJMP134

• DOI: 10.1111/mmi.13725
• Publication Date: 2017-06-14T08:46:49Z
• Authors: Huanjie Li; Juan Li; Chuanjuan Lü; Yongzhen Xia; Yufeng Xin; Honglei Liu; Luying Xun; Huaiwei Liu
• Keywords: 0301 basic medicine; Cupriavidus; Thiosulfates; Gene Expression Regulation, Bacterial; Sulfides; 03 medical and health sciences; Genes, Regulator; Operon; Amino Acid Sequence; Cysteine; Oxidation-Reduction; Conserved Sequence; Sulfur; Transcription Factors

SummarySome heterotrophic bacteria are able to oxidize sulfide (H2S, HS− and S2−) to sulfite and thiosulfate via polysulfide. The genes coding for the oxidation enzymes in Cupriavidus pinatubonensis JMP134 have recently been identified; however, their regulation is unknown. A regulator gene is adjacent to the operon of the sulfide‐oxidizing genes, encoding a σ54‐dependent transcription factor (FisR) with three domains: an R domain, an AAA+ domain and a DNA‐binding domain. Here it is reported that the regulator responds to the presence of sulfide and activates the sulfide‐oxidizing genes. FisR binds to its cognate operator at −114 to −135 bp of the transcription start of the operon. When polysulfide reacts with the R domain of FisR through the three conserved cysteine residues (C53, C64 and C71), FisR activates the expression of the operon. FisR is highly sensitive to polysulfide, activating σ54‐dependent transcription of sulfide‐oxidizing genes for sulfide removal. Further, sequence analysis indicates that FisR‐type regulators are relatively common for controlling sulfide‐oxidizing genes under sulfide stress in the Proteobacteria.