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Regulation of tryptophan biosynthesis in Methanobacterium thermoautotrophicum Marburg

Gast, D. A. and Jenal, U. and Wasserfallen, A. and Leisinger, T.. (1994) Regulation of tryptophan biosynthesis in Methanobacterium thermoautotrophicum Marburg. Journal of bacteriology, Vol. 176, H. 15. pp. 4590-4596.

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Official URL: http://edoc.unibas.ch/dok/A5258574

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Abstract

A tryptophan-auxotrophic mutant of the archaeon Methanobacterium thermoautotrophicum Marburg was grown with growth-promoting and growth-limiting concentrations of tryptophan. The specific activities of anthranilate synthase (TrpEG) and tryptophan synthase (TrpB) increased 30- to 40-fold in tryptophan-starved cells. Levels of trpE-specific and trpD-specific mRNAs (transcripts of the first and the last genes, respectively, of the M. thermoautotrophicum Marburg trp gene cluster) increased about 10-fold upon starvation for tryptophan. Thus, the expression of the trp genes appears to be regulated primarily at the level of transcription. These data support transcription of trp genes as an operon and support a regulatory model involving a repressor. Anthranilate synthase was feedback inhibited by L-tryptophan, with a Ki of 3.0 microM. In a leucine-auxotrophic mutant starved for L-leucine, the level of alpha-isopropylmalate synthase (LeuA) was 10-fold higher than in cells grown with L-leucine. In addition to the finding of specific regulation of gene expression by the end products of their respective pathways, it was found that the levels of anthranilate synthase and alpha-isopropylmalate synthase were reduced upon growth in the presence of amino acids of other families, such as L-alanine, L-proline, or L-arginine. Conversely, starvation for tryptophan caused a slight elevation of alpha-isopropylmalate synthase and starvation for leucine caused a significant increase of anthranilate synthase and tryptophan synthase specific activities. The latter effect was also observed at the level of trp-specific mRNA and is reminiscent of general amino acid control.
Faculties and Departments:05 Faculty of Science > Departement Biozentrum > Infection Biology > Molecular Microbiology (Jenal)
05 Faculty of Science > Departement Biozentrum > Growth & Development > Molecular Microbiology (Jenal)
UniBasel Contributors:Jenal, Urs
Item Type:Article, refereed
Article Subtype:Research Article
Bibsysno:Link to catalogue
Publisher:American Society for Microbiology
ISSN:1098-5530
Note:Publication type according to Uni Basel Research Database: Journal article
Last Modified:22 Mar 2012 14:20
Deposited On:22 Mar 2012 13:20

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