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Two-component signal transduction system CBO0787/CBO0786 represses transcription from botulinum neurotoxin promoters in Clostridium botulinum ATCC 3502.

ABSTRACT: Blocking neurotransmission, botulinum neurotoxin is the most poisonous biological substance known to mankind. Despite its infamy as the scourge of the food industry, the neurotoxin is increasingly used as a pharmaceutical to treat an expanding range of muscle disorders. Whilst neurotoxin expression by the spore-forming bacterium Clostridium botulinum appears tightly regulated, to date only positive regulatory elements, such as the alternative sigma factor BotR, have been implicated in this control. The identification of negative regulators has proven to be elusive. Here, we show that the two-component signal transduction system CBO0787/CBO0786 negatively regulates botulinum neurotoxin expression. Single insertional inactivation of cbo0787 encoding a sensor histidine kinase, or of cbo0786 encoding a response regulator, resulted in significantly elevated neurotoxin gene expression levels and increased neurotoxin production. Recombinant CBO0786 regulator was shown to bind to the conserved -10 site of the core promoters of the ha and ntnh-botA operons, which encode the toxin structural and accessory proteins. Increasing concentration of CBO0786 inhibited BotR-directed transcription from the ha and ntnh-botA promoters, demonstrating direct transcriptional repression of the ha and ntnh-botA operons by CBO0786. Thus, we propose that CBO0786 represses neurotoxin gene expression by blocking BotR-directed transcription from the neurotoxin promoters. This is the first evidence of a negative regulator controlling botulinum neurotoxin production. Understanding the neurotoxin regulatory mechanisms is a major target of the food and pharmaceutical industries alike.

SUBMITTER: Zhang Z

PROVIDER: S-EPMC3610760 | biostudies-literature | 2013 Mar

REPOSITORIES: biostudies-literature

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Two-component signal transduction system CBO0787/CBO0786 represses transcription from botulinum neurotoxin promoters in Clostridium botulinum ATCC 3502.

Zhang Zhen Z Korkeala Hannu H Dahlsten Elias E Sahala Elina E Heap John T JT Minton Nigel P NP Lindström Miia M

PLoS pathogens 20130328 3

Blocking neurotransmission, botulinum neurotoxin is the most poisonous biological substance known to mankind. Despite its infamy as the scourge of the food industry, the neurotoxin is increasingly used as a pharmaceutical to treat an expanding range of muscle disorders. Whilst neurotoxin expression by the spore-forming bacterium Clostridium botulinum appears tightly regulated, to date only positive regulatory elements, such as the alternative sigma factor BotR, have been implicated in this contr ...[more]

PMID: 23555260

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Project description:Profound understanding of the mechanisms foodborne pathogenic bacteria utilize in adaptation to the environmental stress they encounter during food processing and storage is of paramount importance in design of control measures. Chill temperature is a central control measure applied in minimally processed foods; however, data on the mechanisms the foodborne pathogen Clostridium botulinum activates upon cold stress are scarce. Global gene expression analysis on the C.M-BM- botulinum ATCC 3502 strain upon temperature downshift from 37 M-BM-0C to 15M-BM- M-BM-0C was performed to identify the cold-responsive gene set of this organism. Significant up- or down-regulation of 16 and 11 genes, respectively, was observed already 1 h after the cold shock. At 5 h after the temperature downshift, 199 and 210 genes were up- and down-regulated, respectively. Thus, the cold shock rapidly affected the expression of a gene set of a relatively small size, indicating a targeted acute response to cold shock, whereas extensive metabolic remodeling took place after prolonged exposure to cold. Induction of genes related to fatty acid biosynthesis, oxidative stress response, and iron uptake and storage was observed, in addition to mechanisms previously characterized as cold-tolerance related in bacteria. Furthermore, induction of several uncharacterized DNA-binding transcriptional regulator-encoding genes was observed, suggesting involvement of novel regulatory mechanisms in the cold shock response of C.M-BM- botulinum. The role of such regulatory proteins, CBO0477 and CBO0558A, in cold tolerance of C.M-BM- botulinum ATCC 3502 was demonstrated by the deteriorated growth of mutants of the respective genes at 17M-BM- M-BM-0C. C. botulinum ATCC 3502 wild type cold-shocked vs. pre-cold-shock; 3 replicates; growth at 37C in TPGY broth batch culture and subjected to cold shock to 15C; sampling at mid-log growth phase before cold shock, and 1 h and 5 h after temperature downshift to 15C (= 3 time points). Dye-swapped hybridization.

Dataset Information

Two-component signal transduction system CBO0787/CBO0786 represses transcription from botulinum neurotoxin promoters in Clostridium botulinum ATCC 3502.

Publications

Two-component signal transduction system CBO0787/CBO0786 represses transcription from botulinum neurotoxin promoters in Clostridium botulinum ATCC 3502.

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