Toxin production by Clostridium difficile in a defined medium with limited amino acids

Yamakawa, Kiyotaka; Kamiya, Shigeru; Xiao, Meng; Karasawa, Tadahiro; Nakamura, Shinichi

doi:10.1099/00222615-41-5-319

Cited by 42 publications

(36 citation statements)

References 20 publications

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“…Nine amino acids -tryptophan, methionine, valine, iso leucine, proline, leucine, cysteine, glycine and threonine [8] -from the 18 amino acids in the defined medium of Haslam et al [9] were selected for the development of a defined medium to achieve better toxin production. The first seven amino acids are essential for bacterial growth and the last two are growth-enhancing [6, lo].…”

Section: Introductionmentioning

confidence: 99%

Inhibition of enhanced toxin production by Clostridium difficile in biotin-limited conditions

Yamakawa¹,

Karasawa²,

Ohta³

et al. 1998

Journal of Medical Microbiology

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Production of toxins A and B by Clostridium difficile is enhanced in a defined medium with biotin-limited conditions. In the present study compounds inhibitory to enhanced toxin production by a C. dij$jjcile strain were examined. Increases in biotin concentration from 0.05 nM to 50 nM accelerated growth and inhibited enhanced toxin production. Asparagine, glutamic acid and glutamine (10 mM) showed an effect on growth and toxin production similar to that of biotin. Lysine (10 mM) suppressed growth and inhibited toxin production. Addition of these toxin-inhibitory compounds within an incubation period of 2 days inhibited the enhanced toxin production, but later addition showed only slight inhibition of toxin production. Amino acids contained in the defined medium under the biotin-limited conditions were actively utilised in the presence of the three toxin-inhibitory amino acids, but in the presence of lysine, amino-acid utilisation was suppressed. Different mechanisms of action of these toxin-inhibitory molecules, which may be divided into excess biotin, asparagine-glutamic acid-glutamine group, and lysine, are discussed.

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Section: Introductionmentioning

confidence: 99%

Inhibition of enhanced toxin production by Clostridium difficile in biotin-limited conditions

Yamakawa¹,

Karasawa²,

Ohta³

et al. 1998

Journal of Medical Microbiology

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“…If a rapidly metabolizable carbon source, such as glucose, is present in the medium, however, the tox genes remain repressed even many hours after cells enter the stationary phase (7). Other physiological conditions, such as the presence of biotin (45) and certain amino acids (16,(19)(20)(21)44), also contribute to the regulation of tox gene expression by unknown mechanisms.…”

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confidence: 99%

Environmental Response and Autoregulation of Clostridium difficile TxeR, a Sigma Factor for Toxin Gene Expression

et al. 2002

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TxeR, a sigma factor that directs Clostridium difficile RNA polymerase to recognize the promoters of two major toxin genes, was shown to stimulate its own synthesis. Whether expressed in C. difficile, Clostridium perfringens, or Escherichia coli, TxeR stimulated transcription of fusions of the txeR promoter region to reporter genes. As is the case for the tox genes, txeR expression was responsive to the cellular growth phase and the constituents of the medium. That is, the level of expression in broth culture was low during the exponential growth phase, but rapidly increased as cells approached the stationary phase. In the presence of excess glucose, expression from the txeR promoter was repressed. The results support a model for toxin gene expression in which synthesis of TxeR is induced by specific environmental signals. The increased level of TxeR then permits high-level expression of the toxin genes.

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“…Synthesis increases as cells enter stationary phase (6,7) and is stimulated or inhibited by various amino acids present in the medium (8)(9)(10)(11), stimulated by butyric acid but inhibited by butanol (12), repressed by rapidly metabolizable carbon sources (7), induced by addition of certain antibiotics (13), and stimulated by biotin limitation (14). However, the regulation of toxin synthesis is poorly understood at the molecular level, as is the mechanism that triggers an increase in the level of toxin synthesis leading to the transition from mild diarrhea to the potentially lethal PMC.…”

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confidence: 99%

Regulation of toxin synthesis in Clostridium difficile by an alternative RNA polymerase sigma factor

Mani

Dupuy²

2001

Proc. Natl. Acad. Sci. U.S.A.

222

246

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Clostridium difficile, a causative agent of antibiotic-associated diarrhea and its potentially lethal form, pseudomembranous colitis, produces two large protein toxins that are responsible for the cellular damage associated with the disease. The level of toxin production appears to be critical for determining the severity of the disease, but the mechanism by which toxin synthesis is regulated is unknown. The product of a gene, txeR, that lies just upstream of the tox gene cluster was shown to be needed for tox gene expression in vivo and to activate promoter-specific transcription of the tox genes in vitro in conjunction with RNA polymerases from C. difficile, Bacillus subtilis, or Escherichia coli. TxeR was shown to function as an alternative sigma factor for RNA polymerase. Because homologs of TxeR regulate synthesis of toxins and a bacteriocin in other Clostridium species, TxeR appears to be a prototype for a novel mode of regulation of toxin genes.

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Toxin production by Clostridium difficile in a defined medium with limited amino acids

Cited by 42 publications

References 20 publications

Inhibition of enhanced toxin production by Clostridium difficile in biotin-limited conditions

Inhibition of enhanced toxin production by Clostridium difficile in biotin-limited conditions

Environmental Response and Autoregulation of Clostridium difficile TxeR, a Sigma Factor for Toxin Gene Expression

Regulation of toxin synthesis in Clostridium difficile by an alternative RNA polymerase sigma factor

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