Dataset Information

Chlorobaculum tepidum TLS displays a complex transcriptional response to sulfide addition.

ABSTRACT: Chlorobaculum tepidum is a green sulfur bacterium (GSB) that is a model system for phototrophic sulfur oxidation. Despite over 2 decades of research, conspicuous gaps exist in our understanding of its electron donor metabolism and regulation. RNA sequencing (RNA-seq) was used to provide a global picture of the C. tepidum transcriptome during growth on thiosulfate as the sole electron donor and at time points following the addition of sulfide to such a culture. Following sulfide addition, 121 to 150 protein-coding genes displayed significant changes in expression depending upon the time point. These changes included a rapid decrease in expression of thiosulfate and elemental sulfur oxidation genes. Genes and gene loci with increased expression included CT1087, encoding a sulfide:quinone oxidoreductase required for growth in high sulfide concentrations; a polysulfide reductase-like complex operon, psrABC (CT0496 to CT0494); and, surprisingly, a large cluster of genes involved in iron acquisition. Finally, two genes that are conserved as a cassette in anaerobic bacteria and archaea, CT1276 and CT1277, displayed a strong increase in expression. The CT1277 gene product contains a DNA-binding domain, suggesting a role for it in sulfide-dependent gene expression changes.

SUBMITTER: Eddie BJ

PROVIDER: S-EPMC3553837 | biostudies-literature | 2013 Jan

REPOSITORIES: biostudies-literature

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Chlorobaculum tepidum TLS displays a complex transcriptional response to sulfide addition.

Eddie Brian J BJ Hanson Thomas E TE

Journal of bacteriology 20121116 2

Chlorobaculum tepidum is a green sulfur bacterium (GSB) that is a model system for phototrophic sulfur oxidation. Despite over 2 decades of research, conspicuous gaps exist in our understanding of its electron donor metabolism and regulation. RNA sequencing (RNA-seq) was used to provide a global picture of the C. tepidum transcriptome during growth on thiosulfate as the sole electron donor and at time points following the addition of sulfide to such a culture. Following sulfide addition, 121 to ...[more]

PMID: 23161024

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Project description:The green sulfur bacteria (Chlorobiaceae) are anaerobes that use electrons from reduced sulfur compounds (sulfide, S0, and thiosulfate) as electron donors for photoautotrophic growth. Chlorobaculum tepidum, the model system for the Chlorobiaceae, both produces and consumes extracellular S0 globules depending on the availability of sulfide in the environment. These physiological changes imply significant changes in gene regulation, which has been observed when sulfide is added to Cba. tepidum growing on thiosulfate. However, the underlying mechanisms driving these gene expression changes, i.e., the specific regulators and promoter elements involved, have not yet been defined. Here, differential RNA sequencing (dRNA-seq) was used to globally identify transcript start sites (TSS) that were present during growth on sulfide, biogenic S0, and thiosulfate as sole electron donors. TSS positions were used in combination with RNA-seq data from cultures growing on these same electron donors to identify both basal promoter elements and motifs associated with electron donor-dependent transcriptional regulation. These motifs were conserved across homologous Chlorobiaceae promoters. Two lines of evidence suggest that sulfide-mediated repression is the dominant regulatory mode in Cba. tepidum First, motifs associated with genes regulated by sulfide overlap key basal promoter elements. Second, deletion of the Cba. tepidum1277 (CT1277) gene, encoding a putative regulatory protein, leads to constitutive overexpression of the sulfide:quinone oxidoreductase CT1087 in the absence of sulfide. The results suggest that sulfide is the master regulator of sulfur metabolism in Cba. tepidum and the Chlorobiaceae Finally, the identification of basal promoter elements with differing strengths will further the development of synthetic biology in Cba. tepidum and perhaps other ChlorobiaceaeIMPORTANCE Elemental sulfur is a key intermediate in biogeochemical sulfur cycling. The photoautotrophic green sulfur bacterium Chlorobaculum tepidum either produces or consumes elemental sulfur depending on the availability of sulfide in the environment. Our results reveal transcriptional dynamics of Chlorobaculum tepidum on elemental sulfur and increase our understanding of the mechanisms of transcriptional regulation governing growth on different reduced sulfur compounds. This report identifies genes and sequence motifs that likely play significant roles in the production and consumption of elemental sulfur. Beyond this focused impact, this report paves the way for the development of synthetic biology in Chlorobaculum tepidum and other Chlorobiaceae by providing a comprehensive identification of promoter elements for control of gene expression, a key element of strain engineering.

Dataset Information

Chlorobaculum tepidum TLS displays a complex transcriptional response to sulfide addition.

Publications

Chlorobaculum tepidum TLS displays a complex transcriptional response to sulfide addition.

Similar Datasets

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