title: C1 metabolism in Corynebacterium glutamicum: an endogenous pathway for oxidation of methanol to carbon dioxide.
abstract: Methanol is considered an interesting carbon source in "bio-based" microbial production processes. Since Corynebacterium glutamicum is an important host in industrial biotechnology, in particular for amino acid production, we performed studies of the response of this organism to methanol. The C. glutamicum wild type was able to convert (13)C-labeled methanol to (13)CO2. Analysis of global gene expression in the presence of methanol revealed several genes of ethanol catabolism to be upregulated, 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 Δald ΔadhE and Δald ΔmshC deletion mutants 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 the case with 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 endogenous pathway for methanol oxidation to CO2 and to identify the enzymes and a transcriptional regulator involved in this pathway.
authors.affiliation: Institute of Bio- and Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich, Jülich, Germany.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Witthoff
authors.forename: Alice
authors.initials: A
authors.lastname: Mühlroth
authors.forename: Jan
authors.initials: J
authors.lastname: Marienhagen
authors.forename: Michael
authors.initials: M
authors.lastname: Bott
mesh_terms: D000426:Alcohol Dehydrogenase / Q000235:genetics / Q000378:metabolism; D000445:Aldehyde Oxidoreductases / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002244:Carbon / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism*; D048230:Corynebacterium glutamicum / Q000201:enzymology* / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D000431:Ethanol / Q000378:metabolism; D005557:Formaldehyde / Q000378:metabolism; D005560:Formate Dehydrogenases / Q000235:genetics / Q000378:metabolism; D005561:Formates / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D005947:Glucose / Q000378:metabolism; D000432:Methanol / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D010084:Oxidation-Reduction; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D005561:Formates; D011994:Recombinant Proteins; C030544:formic acid; D002245:Carbon Dioxide; D005557:Formaldehyde; D000431:Ethanol; D002244:Carbon; D000426:Alcohol Dehydrogenase; D005560:Formate Dehydrogenases; D000445:Aldehyde Oxidoreductases; C108807:mycothiol-dependent formaldehyde dehydrogenase; C018699:aldehyde dehydrogenase (NAD(P)+); D005947:Glucose; D000432:Methanol