Catabolic regulation analysis of <it>Escherichia coli </it>and its <it>crp, mlc, mgsA, pgi </it>and <it>ptsG </it>mutants
<p>Abstract</p> <p>Background</p> <p>Most bacteria can use various compounds as carbon sources. These carbon sources can be either co-metabolized or sequentially metabolized, where the latter phenomenon typically occurs as catabolite repression. From the practical appli...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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BMC
2011-08-01
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| Series: | Microbial Cell Factories |
| Online Access: | http://www.microbialcellfactories.com/content/10/1/67 |
| _version_ | 1818146746627260416 |
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| author | Yao Ruilian Hirose Yuki Sarkar Dayanidhi Nakahigashi Kenji Ye Qin Shimizu Kazuyuki |
| author_facet | Yao Ruilian Hirose Yuki Sarkar Dayanidhi Nakahigashi Kenji Ye Qin Shimizu Kazuyuki |
| author_sort | Yao Ruilian |
| collection | DOAJ |
| description | <p>Abstract</p> <p>Background</p> <p>Most bacteria can use various compounds as carbon sources. These carbon sources can be either co-metabolized or sequentially metabolized, where the latter phenomenon typically occurs as catabolite repression. From the practical application point of view of utilizing lignocellulose for the production of biofuels etc., it is strongly desirable to ferment all sugars obtained by hydrolysis from lignocellulosic materials, where simultaneous consumption of sugars would benefit the formation of bioproducts. However, most organisms consume glucose prior to consumption of other carbon sources, and exhibit diauxic growth. It has been shown by fermentation experiments that simultaneous consumption of sugars can be attained by <it>ptsG, mgsA </it>mutants etc., but its mechanism has not been well understood. It is strongly desirable to understand the mechanism of metabolic regulation for catabolite regulation to improve the performance of fermentation.</p> <p>Results</p> <p>In order to make clear the catabolic regulation mechanism, several continuous cultures were conducted at different dilution rates of 0.2, 0.4, 0.6 and 0.7 h<sup>-1 </sup>using wild type <it>Escherichia coli</it>. The result indicates that the transcript levels of global regulators such as <it>crp, cra, mlc </it>and <it>rpoS </it>decreased, while those of <it>fadR, iclR, soxR/S </it>increased as the dilution rate increased. These affected the metabolic pathway genes, which in turn affected fermentation result where the specific glucose uptake rate, the specific acetate formation rate, and the specific CO<sub>2 </sub>evolution rate (CER) were increased as the dilution rate was increased. This was confirmed by the <sup>13</sup>C-flux analysis. In order to make clear the catabolite regulation, the effect of <it>crp </it>gene knockout (Δ<it>crp</it>) and crp enhancement (<it>crp<sup>+</sup></it>) as well as <it>mlc, mgsA, pgi </it>and <it>ptsG </it>gene knockout on the metabolism was then investigated by the continuous culture at the dilution rate of 0.2 h<sup>-1 </sup>and by some batch cultures. In the case of Δ<it>crp </it>(and also Δ<it>mlc</it>) mutant, TCA cycle and glyoxylate were repressed, which caused acetate accumulation. In the case of <it>crp<sup>+ </sup></it>mutant, glycolysis, TCA cycle, and gluconeogenesis were activated, and simultaneous consumption of multiple carbon sources can be attained, but the glucose consumption rate became less due to repression of <it>ptsG </it>and <it>ptsH </it>by the activation of Mlc. Simultaneous consumption of multiple carbon sources could be attained by <it>mgsA, pgi</it>, and <it>ptsG </it>mutants due to increase in <it>crp </it>as well as <it>cyaA</it>, while glucose consumption rate became lower.</p> <p>Conclusions</p> <p>The transcriptional catabolite regulation mechanism was made clear for the wild type <it>E. coli</it>, and its <it>crp, mlc, ptsG, pgi, and mgsA </it>gene knockout mutants. The results indicate that catabolite repression can be relaxed and <it>crp </it>as well as <it>cyaA </it>can be increased by <it>crp<sup>+</sup>, mgsA, pgi</it>, and <it>ptsG </it>mutants, and thus simultaneous consumption of multiple carbon sources including glucose can be made, whereas the glucose uptake rate became lower as compared to wild type due to inactivation of <it>ptsG </it>in all the mutants considered.</p> |
| first_indexed | 2024-12-11T12:24:15Z |
| format | Article |
| id | doaj.art-57e7c97cd2294f0fa3a6823eec96eb68 |
| institution | Directory Open Access Journal |
| issn | 1475-2859 |
| language | English |
| last_indexed | 2024-12-11T12:24:15Z |
| publishDate | 2011-08-01 |
| publisher | BMC |
| record_format | Article |
| series | Microbial Cell Factories |
| spelling | doaj.art-57e7c97cd2294f0fa3a6823eec96eb682022-12-22T01:07:26ZengBMCMicrobial Cell Factories1475-28592011-08-011016710.1186/1475-2859-10-67Catabolic regulation analysis of <it>Escherichia coli </it>and its <it>crp, mlc, mgsA, pgi </it>and <it>ptsG </it>mutantsYao RuilianHirose YukiSarkar DayanidhiNakahigashi KenjiYe QinShimizu Kazuyuki<p>Abstract</p> <p>Background</p> <p>Most bacteria can use various compounds as carbon sources. These carbon sources can be either co-metabolized or sequentially metabolized, where the latter phenomenon typically occurs as catabolite repression. From the practical application point of view of utilizing lignocellulose for the production of biofuels etc., it is strongly desirable to ferment all sugars obtained by hydrolysis from lignocellulosic materials, where simultaneous consumption of sugars would benefit the formation of bioproducts. However, most organisms consume glucose prior to consumption of other carbon sources, and exhibit diauxic growth. It has been shown by fermentation experiments that simultaneous consumption of sugars can be attained by <it>ptsG, mgsA </it>mutants etc., but its mechanism has not been well understood. It is strongly desirable to understand the mechanism of metabolic regulation for catabolite regulation to improve the performance of fermentation.</p> <p>Results</p> <p>In order to make clear the catabolic regulation mechanism, several continuous cultures were conducted at different dilution rates of 0.2, 0.4, 0.6 and 0.7 h<sup>-1 </sup>using wild type <it>Escherichia coli</it>. The result indicates that the transcript levels of global regulators such as <it>crp, cra, mlc </it>and <it>rpoS </it>decreased, while those of <it>fadR, iclR, soxR/S </it>increased as the dilution rate increased. These affected the metabolic pathway genes, which in turn affected fermentation result where the specific glucose uptake rate, the specific acetate formation rate, and the specific CO<sub>2 </sub>evolution rate (CER) were increased as the dilution rate was increased. This was confirmed by the <sup>13</sup>C-flux analysis. In order to make clear the catabolite regulation, the effect of <it>crp </it>gene knockout (Δ<it>crp</it>) and crp enhancement (<it>crp<sup>+</sup></it>) as well as <it>mlc, mgsA, pgi </it>and <it>ptsG </it>gene knockout on the metabolism was then investigated by the continuous culture at the dilution rate of 0.2 h<sup>-1 </sup>and by some batch cultures. In the case of Δ<it>crp </it>(and also Δ<it>mlc</it>) mutant, TCA cycle and glyoxylate were repressed, which caused acetate accumulation. In the case of <it>crp<sup>+ </sup></it>mutant, glycolysis, TCA cycle, and gluconeogenesis were activated, and simultaneous consumption of multiple carbon sources can be attained, but the glucose consumption rate became less due to repression of <it>ptsG </it>and <it>ptsH </it>by the activation of Mlc. Simultaneous consumption of multiple carbon sources could be attained by <it>mgsA, pgi</it>, and <it>ptsG </it>mutants due to increase in <it>crp </it>as well as <it>cyaA</it>, while glucose consumption rate became lower.</p> <p>Conclusions</p> <p>The transcriptional catabolite regulation mechanism was made clear for the wild type <it>E. coli</it>, and its <it>crp, mlc, ptsG, pgi, and mgsA </it>gene knockout mutants. The results indicate that catabolite repression can be relaxed and <it>crp </it>as well as <it>cyaA </it>can be increased by <it>crp<sup>+</sup>, mgsA, pgi</it>, and <it>ptsG </it>mutants, and thus simultaneous consumption of multiple carbon sources including glucose can be made, whereas the glucose uptake rate became lower as compared to wild type due to inactivation of <it>ptsG </it>in all the mutants considered.</p>http://www.microbialcellfactories.com/content/10/1/67 |
| spellingShingle | Yao Ruilian Hirose Yuki Sarkar Dayanidhi Nakahigashi Kenji Ye Qin Shimizu Kazuyuki Catabolic regulation analysis of <it>Escherichia coli </it>and its <it>crp, mlc, mgsA, pgi </it>and <it>ptsG </it>mutants Microbial Cell Factories |
| title | Catabolic regulation analysis of <it>Escherichia coli </it>and its <it>crp, mlc, mgsA, pgi </it>and <it>ptsG </it>mutants |
| title_full | Catabolic regulation analysis of <it>Escherichia coli </it>and its <it>crp, mlc, mgsA, pgi </it>and <it>ptsG </it>mutants |
| title_fullStr | Catabolic regulation analysis of <it>Escherichia coli </it>and its <it>crp, mlc, mgsA, pgi </it>and <it>ptsG </it>mutants |
| title_full_unstemmed | Catabolic regulation analysis of <it>Escherichia coli </it>and its <it>crp, mlc, mgsA, pgi </it>and <it>ptsG </it>mutants |
| title_short | Catabolic regulation analysis of <it>Escherichia coli </it>and its <it>crp, mlc, mgsA, pgi </it>and <it>ptsG </it>mutants |
| title_sort | catabolic regulation analysis of it escherichia coli it and its it crp mlc mgsa pgi it and it ptsg it mutants |
| url | http://www.microbialcellfactories.com/content/10/1/67 |
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