title: The Two-Component System RsrS-RsrR Regulates the Tetrathionate Intermediate Pathway for Thiosulfate Oxidation inAcidithiobacillus caldus.
abstract: Acidithiobacillus caldus(A. caldus) is a common bioleaching bacterium that possesses a sophisticated and highly efficient inorganic sulfur compound metabolism network. Thiosulfate, a central intermediate in the sulfur metabolism network ofA. caldusand other sulfur-oxidizing microorganisms, can be metabolized via the tetrathionate intermediate (S4I) pathway catalyzed by thiosulfate:quinol oxidoreductase (Tqo or DoxDA) and tetrathionate hydrolase (TetH). InA. caldus, there is an additional two-component system called RsrS-RsrR. SincersrSandrsrRare arranged as an operon withdoxDAandtetHin the genome, we suggest that the regulation of the S4I pathway may occur via the RsrS-RsrR system. To examine the regulatory role of the two-component system RsrS-RsrR on the S4I pathway, ΔrsrRand ΔrsrSstrains were constructed inA. caldususing a newly developed markerless gene knockout method. Transcriptional analysis of thetetHcluster in the wild type and mutant strains revealed positive regulation of the S4I pathway by the RsrS-RsrR system. A 19 bp inverted repeat sequence (IRS, AACACCTGTTACACCTGTT) located upstream of thetetHpromoter was identified as the binding site for RsrR by using electrophoretic mobility shift assays (EMSAs)in vitroand promoter-probe vectorsin vivo. In addition, ΔrsrR, and ΔrsrSstrains cultivated in K2S4O6-medium exhibited significant growth differences when compared with the wild type. Transcriptional analysis indicated that the absence ofrsrSorrsrRhad different effects on the expression of genes involved in sulfur metabolism and signaling systems. Finally, a model of tetrathionate sensing by RsrS, signal transduction via RsrR, and transcriptional activation oftetH-doxDAwas proposed to provide insights toward the understanding of sulfur metabolism inA. caldus. This study also provided a powerful genetic tool for studies inA. caldus.
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong University Jinan, China.
authors.forename: Zhao-Bao
authors.initials: ZB
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong University Jinan, China.
authors.forename: Ya-Qing
authors.initials: YQ
authors.lastname: Li
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong University Jinan, China.
authors.forename: Jian-Qun
authors.initials: JQ
authors.lastname: Lin
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong University Jinan, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Pang
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong University Jinan, China.
authors.forename: Xiang-Mei
authors.initials: XM
authors.lastname: Liu
authors.affiliation: School of Mathematics, Shandong University Jinan, China.
authors.forename: Bing-Qiang
authors.initials: BQ
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong University Jinan, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong University Jinan, China.
authors.forename: Cheng-Jia
authors.initials: CJ
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong University Jinan, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Wu
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong University Jinan, China.
authors.forename: Jian-Qiang
authors.initials: JQ
authors.lastname: Lin
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong University Jinan, China.
authors.forename: Lin-Xu
authors.initials: LX
authors.lastname: Chen
keywords: Acidithiobacillus caldus; RsrS-RsrR; S4I pathway; cis regulatory element; sulfur metabolism; thiosulfate oxidation; transcriptional regulation; two-component system