The second subunit of methanol dehydrogenase of Methylobacterium extorquens AM1.
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ABSTRACT:
SUBMITTER: Nunn DN
PROVIDER: S-EPMC1138755 | biostudies-other | 1989 Jun
REPOSITORIES: biostudies-other
Similar Datasets
Project description:Methylobacterium extorquens AM1 on methanol
2012-02-28 | PRD000446 | Pride
Project description:Methylobacterium extorquens AM1 is a facultative methylotrophic Alphaproteobacterium and has been subject to intense study under pure methylotrophic as well as pure heterotrophic growth conditions in the past. Here, we investigated the metabolism of M. extorquens AM1 under mixed substrate conditions, i.e., in the presence of methanol plus succinate. We found that both substrates were co-consumed, and the carbon conversion was two-thirds from succinate and one-third from methanol relative to mol carbon. (13)C-methanol labeling and liquid chromatography mass spectrometry analyses revealed the different fates of the carbon from the two substrates. Methanol was primarily oxidized to CO(2) for energy generation. However, a portion of the methanol entered biosynthetic reactions via reactions specific to the one-carbon carrier tetrahydrofolate. In contrast, succinate was primarily used to provide precursor metabolites for bulk biomass production. This work opens new perspectives on the role of methylotrophy when substrates are simultaneously available, a situation prevailing under environmental conditions.
| S-EPMC3486813 | biostudies-literature
Project description:In order to provide information about the gene expression response that occurs when cells experience a change in carbon source, succinate limited chemostat cultures of Methylobacterium extorquens AM1 were grown to and maintained at an OD of ~0.63, transferred to flasks and methanol was added. Cells were harvested for RNA extraction at time: 0 min, 10 min, 30 min, 1 hr, 2 hr, 4 hr and 6 hr post transition. At 30 min, a no methanol addition sample was extracted as a carbon starvation control. These data were used in conjunction with flux, enzymatic and metabolite measurements to assess the changes in central metabolism during this transition. Abstract from manuscript: When organisms experience environmental change, how does their metabolic network reset and adapt to the new condition? This study focused on the mechanisms of metabolic adaptation occurring during the transition from succinate to methanol growth by the methylotrophic bacterium Methylobacterium extorquens, analyzing changes in carbon flux, gene expression, metabolites and enzymatic activities over time. Initially, cells experienced metabolic imbalance with excretion of metabolites, changes in nucleotide levels and cessation of cell growth. Though assimilatory pathways were induced rapidly, a transient block in carbon flow to biomass synthesis occurred, and enzymatic assays suggested methylenetetrahydrofolate dehydrogenase as one control point. This “downstream priming” mechanism ensures that significant carbon flux through these pathways does not occur until they are fully induced, precluding the buildup of toxic intermediates. Most metabolites that are required for growth on both carbon sources did not change significantly, even though transcripts and enzymatic activities required for their production changed radically, underscoring the concept of metabolic setpoints.
2011-08-01 | GSE22031 | GEO
Project description:Formate dehydrogenase has traditionally been assumed to play an essential role in energy generation during growth on C(1) compounds. However, this assumption has not yet been experimentally tested in methylotrophic bacteria. In this study, a whole-genome analysis approach was used to identify three different formate dehydrogenase systems in the facultative methylotroph Methylobacterium extorquens AM1 whose expression is affected by either molybdenum or tungsten. A complete set of single, double, and triple mutants was generated, and their phenotypes were analyzed. The growth phenotypes of the mutants suggest that any one of the three formate dehydrogenases is sufficient to sustain growth of M. extorquens AM1 on formate, while surprisingly, none is required for growth on methanol or methylamine. Nuclear magnetic resonance analysis of the fate of [(13)C]methanol revealed that while cells of wild-type M. extorquens AM1 as well as cells of all the single and the double mutants continuously produced [(13)C]bicarbonate and (13)CO(2), cells of the triple mutant accumulated [(13)C]formate instead. Further studies of the triple mutant showed that formate was not produced quantitatively and was consumed later in growth. These results demonstrated that all three formate dehydrogenase systems must be inactivated in order to disrupt the formate-oxidizing capacity of the organism but that an alternative formate-consuming capacity exists in the triple mutant.
| S-EPMC303455 | biostudies-literature
Project description:Formaldehyde is toxic for all organisms from bacteria to humans due to its reactivity with biological macromolecules. Organisms that grow aerobically on single-carbon compounds such as methanol and methane face a special challenge in this regard because formaldehyde is a central metabolic intermediate during methylotrophic growth. In the alpha-proteobacterium Methylobacterium extorquens AM1, we found a previously unknown enzyme that efficiently catalyzes the removal of formaldehyde: it catalyzes the condensation of formaldehyde and tetrahydromethanopterin to methylene tetrahydromethanopterin, a reaction which also proceeds spontaneously, but at a lower rate than that of the enzyme-catalyzed reaction. Formaldehyde-activating enzyme (Fae) was purified from M. extorquens AM1 and found to be one of the major proteins in the cytoplasm. The encoding gene is located within a cluster of genes for enzymes involved in the further oxidation of methylene tetrahydromethanopterin to CO(2). Mutants of M. extorquens AM1 defective in Fae were able to grow on succinate but not on methanol and were much more sensitive toward methanol and formaldehyde. Uncharacterized orthologs to this enzyme are predicted to be encoded by uncharacterized genes from archaea, indicating that this type of enzyme occurs outside the methylotrophic bacteria.
| S-EPMC111405 | biostudies-literature
Project description:In order to provide information about the gene expression response that occurs when cells experience a change in carbon source, succinate limited chemostat cultures of Methylobacterium extorquens AM1 were grown to and maintained at an OD of ~0.63, transferred to flasks and methanol was added. Cells were harvested for RNA extraction at time: 0 min, 10 min, 30 min, 1 hr, 2 hr, 4 hr and 6 hr post transition. At 30 min, a no methanol addition sample was extracted as a carbon starvation control. These data were used in conjunction with flux, enzymatic and metabolite measurements to assess the changes in central metabolism during this transition. Abstract from manuscript: When organisms experience environmental change, how does their metabolic network reset and adapt to the new condition? This study focused on the mechanisms of metabolic adaptation occurring during the transition from succinate to methanol growth by the methylotrophic bacterium Methylobacterium extorquens, analyzing changes in carbon flux, gene expression, metabolites and enzymatic activities over time. Initially, cells experienced metabolic imbalance with excretion of metabolites, changes in nucleotide levels and cessation of cell growth. Though assimilatory pathways were induced rapidly, a transient block in carbon flow to biomass synthesis occurred, and enzymatic assays suggested methylenetetrahydrofolate dehydrogenase as one control point. This “downstream priming” mechanism ensures that significant carbon flux through these pathways does not occur until they are fully induced, precluding the buildup of toxic intermediates. Most metabolites that are required for growth on both carbon sources did not change significantly, even though transcripts and enzymatic activities required for their production changed radically, underscoring the concept of metabolic setpoints. Gene expression in succinate limited chemostat cultures was compared to gene expression in cells transferred to flasks before and after methanol addition. As a control, a time = 0 sample (RNA prepared from cells harvested directly from the chemostat) was compared to a time = 0 sample immediately obtained after the cells were transferred to flasks, before methanol was added in order to identify changes due to flask transfer. A carbon starvation control was also done comparing expression from time = 0 (chemostat cells) to cells transferred to flasks for 30 min with no carbon source added. Two biological replicates each with two techinal replicates (dye swap) were analyzed for time = 0 (chemostat) vs 10 min, 30 min, 1 hr and 2 hr after methanol addition. One biological replicate with two technical replicates (dye swap) were analyzed for time = 0 (chemostat) vs time = 0 (flask transfer), and time = 0 (chemostat) vs time = 4 hr, 6 hr and 30 min no methanol addition.
2011-07-31 | E-GEOD-22031 | biostudies-arrayexpress
Project description:Lanthanides are utilized by microbial methanol dehydrogenases, and it has been proposed that lanthanides may be important for other type I alcohol dehydrogenases. A triple mutant strain (mxaF xoxF1 xoxF2; named MDH-3), deficient in the three known methanol dehydrogenases of the model methylotroph Methylobacterium extorquens AM1, is able to grow poorly with methanol if exogenous lanthanides are added to the growth medium. When the gene encoding a putative quinoprotein ethanol dehydrogenase, exaF, was mutated in the MDH-3 background, the quadruple mutant strain could no longer grow on methanol in minimal medium with added lanthanum (La3+). ExaF was purified from cells grown with both calcium (Ca2+) and La3+ and with Ca2+ only, and the protein species were studied biochemically. Purified ExaF is a 126-kDa homodimer that preferentially binds La3+ over Ca2+ in the active site. UV-visible spectroscopy indicates the presence of pyrroloquinoline quinone (PQQ) as a cofactor. ExaF purified from the Ca2+-plus-La3+ condition readily oxidizes ethanol and has secondary activities with formaldehyde, acetaldehyde, and methanol, whereas ExaF purified from the Ca2+-only condition has minimal activity with ethanol as the substrate and activity with methanol is not detectable. The exaF mutant is not affected for growth with ethanol; however, kinetic and in vivo data show that ExaF contributes to ethanol metabolism when La3+ is present, expanding the role of lanthanides to multicarbon metabolism.ImportanceExaF is the most efficient PQQ-dependent ethanol dehydrogenase reported to date and, to our knowledge, the first non-XoxF-type alcohol oxidation system reported to use lanthanides as a cofactor, expanding the importance of lanthanides in biochemistry and bacterial metabolism beyond methanol dehydrogenases to multicarbon metabolism. These results support an earlier proposal that an aspartate residue near the catalytic aspartate residue may be an indicator of rare-earth element utilization by type I alcohol dehydrogenases.
| S-EPMC5075040 | biostudies-literature
Project description:The goal of this study was to use microarrays to identify genes differentially regulated under conditions of formaldehyde stress relative to two other stress conditions (oxidative, osmotic) in an effort to identify genes that might be involved in a formaldehyde-specific stress response, rather than a general stress response, in the model methylotroph Methylobacterium extorquens AM1.
2015-01-01 | GSE15631 | GEO
Project description:Most serine cycle methylotrophic bacteria lack isocitrate lyase and convert acetyl coenzyme A (acetyl-CoA) to glyoxylate via a novel pathway thought to involve butyryl-CoA and propionyl-CoA as intermediates. In this study we have used a genome analysis approach followed by mutation to test a number of genes for involvement in this novel pathway. We show that methylmalonyl-CoA mutase, an R-specific crotonase, isobutyryl-CoA dehydrogenase, and a GTPase are involved in glyoxylate regeneration. We also monitored the fate of (14)C-labeled carbon originating from acetate, butyrate, or bicarbonate in mutants defective in glyoxylate regeneration and identified new potential intermediates in the pathway: ethylmalonyl-CoA, methylsuccinyl-CoA, isobutyryl-CoA, methacrylyl-CoA, and beta-hydroxyisobutyryl-CoA. A new scheme for the pathway is proposed based on these data.
| S-EPMC134890 | biostudies-literature
Project description:The bio-economy relies on microbial strains optimized for efficient large scale production of chemicals and fuels from inexpensive and renewable feedstocks under industrial conditions. The reduced one carbon compound methanol, whose production does not involve carbohydrates needed for the feed and food sector, can be used as sole carbon and energy source by methylotrophic bacteria like Methylobacterium extorquens AM1. This strain has already been engineered to produce various commodity and high value chemicals from methanol. The toxic effect of methanol limits its concentration as feedstock to 1% v/v. We obtained M. extorquens chassis strains tolerant to high methanol via adaptive directed evolution using the GM3 technology of automated continuous culture. Turbidostat and conditional medium swap regimes were employed for the parallel evolution of the recently characterized strain TK 0001 and the reference strain AM1 and enabled the isolation of derivatives of both strains capable of stable growth with 10% methanol. The isolates produced more biomass at 1% methanol than the ancestor strains. Genome sequencing identified the gene metY coding for an O-acetyl-L-homoserine sulfhydrylase as common target of mutation. We showed that the wildtype enzyme uses methanol as substrate at elevated concentrations. This side reaction produces methoxine, a toxic homolog of methionine incorporated in polypeptides during translation. All mutated metY alleles isolated from the evolved populations coded for inactive enzymes, designating O-acetyl-L-homoserine sulfhydrylase as a major vector of methanol toxicity. A whole cell transcriptomic analysis revealed that genes coding for chaperones and proteases were upregulated in the evolved cells as compared with the wildtype, suggesting that the cells had to cope with aberrant proteins formed during the adaptation to increasing methanol exposure. In addition, the expression of ribosomal proteins and enzymes related to energy production from methanol like formate dehydrogenases and ATP synthases was boosted in the evolved cells upon a short-term methanol stress. D-lactate production from methanol by adapted cells overexpressing the native D-lactate dehydrogenase was quantified. A significant higher lactate yield was obtained compared with control cells, indicating an enhanced capacity of the cells resistant to high methanol to assimilate this one carbon feedstock more efficiently.
| S-EPMC6595629 | biostudies-literature