C1 metabolism in Corynebacterium glutamicum: an endogenous pathway for oxidation of methanol to carbon dioxide
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ABSTRACT: Methanol is considered as an interesting carbon source in biobased microbial production processes. As Corynebacterium glutamicum is an important host in industrial biotechnology, in particular for amino acid production, we performed studies on the response of this organism to methanol. C. glutamicum wild type was able to convert 13C-labeled methanol to 13CO2. Analysis of global gene expression in the presence of methanol revealed several genes of ethanol catabolism to be up-regulated, indicating that some of the corresponding enzymes are involved in methanol oxidation. Indeed, a mutant lacking the alcohol dehydrogenase gene adhA showed a 62% reduced methanol consumption rate, indicating that AdhA is mainly responsible for methanol oxidation to formaldehyde. Further studies revealed that oxidation of formaldehyde to formate is catalyzed predominantly by two enzymes, the acetaldehyde dehydrogenase Ald and the mycothiol-dependent formaldehyde dehydrogenase AdhE. The deletion mutants M-oM-^AM-^DaldM-oM-^AM-^DadhE and M-oM-^AM-^DaldM-oM-^AM-^DmshC were severely impaired in their ability to oxidize formaldehyde, but residual methanol oxidation to CO2 was still possible. The oxidation of formate to CO2 is catalyzed by the formate dehydrogenase FdhF recently identified by us. Similar to ethanol, methanol catabolism is subject to carbon catabolite repression in the presence of glucose and is dependent on the transcriptional regulator RamA, which was previously shown to be essential for expression of adhA and ald. In conclusion, we were able to show that C. glutamicum possesses an endogeneous pathway for methanol oxidation to CO2 and to identify the enzymes and a transcriptional regulator involved in this pathway. Whole-genome DNA microarray analyses were performed to monitor changes in the global gene expression of C. glutamicum wild type in response to the presence of methanol.
ORGANISM(S): Corynebacterium glutamicum ATCC 13032
SUBMITTER: Tino Polen
PROVIDER: E-GEOD-49936 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
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