Ethambutol, a cell wall inhibitor of Mycobacterium tuberculosis, elicits l-glutamate efflux of Corynebacterium glutamicum

• Eva Radmacher

  Institute for Biotechnology, Research Centre Jülich, D-52425 Jülich, Germany

• Kathrin C. Stansen

  Institute for Biotechnology, Research Centre Jülich, D-52425 Jülich, Germany

• Gurdyal S. Besra

  School of Biosciences, University of Birmingham, Birmingham B15 2TT, UK

• Luke J. Alderwick

  School of Biosciences, University of Birmingham, Birmingham B15 2TT, UK

• William N. Maughan

  School of Biosciences, University of Birmingham, Birmingham B15 2TT, UK

• Günter Hollweg

  Pathology, University Hospital, D-52074 Aachen, Germany

• Hermann Sahm

  Institute for Biotechnology, Research Centre Jülich, D-52425 Jülich, Germany

• Volker F. Wendisch

  Institute for Biotechnology, Research Centre Jülich, D-52425 Jülich, Germany

• Lothar Eggeling

  Institute for Biotechnology, Research Centre Jülich, D-52425 Jülich, Germany

抄録

Corynebacterium glutamicum is used for the large-scale production of l -glutamate, but the efflux of this amino acid is poorly understood. This study shows that addition of ethambutol (EMB) to growing cultures of C. glutamicum causes l -glutamate efflux at rates of up to 15 nmol min −1 (mg dry wt) −1 , whereas in the absence of EMB, no efflux occurs. EMB is used for the treatment of Mycobacterium tuberculosis , and at a molecular level it targets a series of arabinosyltransferases (EmbCAB). The single arabinosyltransferase-encoding emb gene of C. glutamicum was placed under the control of a Tet repressor (TetR). Experiments with this strain, as well as with an emb -overexpressing strain, coupled with biochemical analyses showed that: (i) emb expression was correlated with l -glutamate efflux, (ii) emb overexpression increased EMB resistance, (iii) EMB caused less arabinan deposition in cell wall arabinogalactan, and (iv) EMB caused a reduced content of cell-wall-bound mycolic acids. Thus EMB addition resulted in a marked disordering of the cell envelope, which was also discernible by examining cellular morphology. In order to further characterize the cellular response to EMB addition, genome-wide expression profiling was performed using DNA microarrays. This identified 76 differentially expressed genes, with 18 of them upregulated more than eightfold. Among these were the cell-wall-related genes ftsE and mepA (encoding a secreted metalloprotease); however, genes of central metabolism were largely absent. Given that an altered lipid composition of the plasma membrane of C. glutamicum can result in l -glutamate efflux, we speculate that major structural alterations of the cell envelope are transmitted to the membrane, which in turn activates an export system, perhaps via increased membrane tension.

収録刊行物

• Microbiology

  Microbiology 151 (5), 1359-1368, 2005-05-01

  Microbiology Society

キーワード

• Microbiology

詳細情報

• CRID: 1363388843891349504
• NII論文ID: 80017303174
• DOI: 10.1099/mic.0.27804-0
• ISSN: 14652080
• ISSN: 13500872
• ISSN: http://id.crossref.org/issn/13500872
• Web Site: https://www.microbiologyresearch.org/content/journal/micro/10.1099/mic.0.27804-0?crawler=true
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