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Rerouting Cellular Electron Flux To Increase the Rate of Biological Methane Production.

Catlett JL, Ortiz AM, Buan NR - Appl. Environ. Microbiol. (2015)

Bottom Line: In Methanosarcina acetivorans, HdrABC expression caused an increased rate of methanogenesis and a decrease in metabolic efficiency on methylotrophic substrates.When acetate was the sole carbon and energy source, neither deletion nor overexpression of HdrABC had an effect on growth or methane production rates.These results suggest that in cells grown on methylated substrates, the cell compensates for energy losses due to expression of HdrABC with an increased rate of substrate turnover and that HdrABC lacks the appropriate electron donor in acetate-grown cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry, Redox Biology Center, University of Nebraska-Lincoln, Lincoln, Nebraska, USA.

No MeSH data available.


Related in: MedlinePlus

Methylotrophic methanogenesis pathway in M. acetivorans. The green ovals indicate energy-conserving steps. The red oval indicates an energy-consuming step. Yellow indicates an [Na+]-dependent energy conservation step. Ac-CoA, acetyl-coenzyme A; Fpo, proton-pumping F420-methanophenazine oxidoreductase; Mtr, methyl-coenzyme M methyltransferase.
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Figure 5: Methylotrophic methanogenesis pathway in M. acetivorans. The green ovals indicate energy-conserving steps. The red oval indicates an energy-consuming step. Yellow indicates an [Na+]-dependent energy conservation step. Ac-CoA, acetyl-coenzyme A; Fpo, proton-pumping F420-methanophenazine oxidoreductase; Mtr, methyl-coenzyme M methyltransferase.

Mentions: The model simulations and flux calculations show that all but one model, M13 (see Table S5 and Fig. S4 in the supplemental material), are excluded by comparing predicted and actual biomass measurements. Model M13 is very similar to our physiological data in that a direct mechanism for CoM-S-S-CoB reduction by reduced ferredoxin is characterized by a 5 to 15% increase in biomass in the ΔhdrABC mutant relative to the parent strain (within the error of experimental ΔhdrABC biomass measurement), a 5 to 10% decrease in biomass in the Δrnf mutant (within the error of experimental Δrnf biomass measurement) (32), and equivalent biomasses between the parent and att::hdrABC* strains. The available data and model predictions suggest that when M. acetivorans is growing on methylotrophic substrates, the role of HdrABC is to bypass Rnf by using electrons from ferredoxin to reduce CoM-S-S-CoB (Fig. 5).


Rerouting Cellular Electron Flux To Increase the Rate of Biological Methane Production.

Catlett JL, Ortiz AM, Buan NR - Appl. Environ. Microbiol. (2015)

Methylotrophic methanogenesis pathway in M. acetivorans. The green ovals indicate energy-conserving steps. The red oval indicates an energy-consuming step. Yellow indicates an [Na+]-dependent energy conservation step. Ac-CoA, acetyl-coenzyme A; Fpo, proton-pumping F420-methanophenazine oxidoreductase; Mtr, methyl-coenzyme M methyltransferase.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4561719&req=5

Figure 5: Methylotrophic methanogenesis pathway in M. acetivorans. The green ovals indicate energy-conserving steps. The red oval indicates an energy-consuming step. Yellow indicates an [Na+]-dependent energy conservation step. Ac-CoA, acetyl-coenzyme A; Fpo, proton-pumping F420-methanophenazine oxidoreductase; Mtr, methyl-coenzyme M methyltransferase.
Mentions: The model simulations and flux calculations show that all but one model, M13 (see Table S5 and Fig. S4 in the supplemental material), are excluded by comparing predicted and actual biomass measurements. Model M13 is very similar to our physiological data in that a direct mechanism for CoM-S-S-CoB reduction by reduced ferredoxin is characterized by a 5 to 15% increase in biomass in the ΔhdrABC mutant relative to the parent strain (within the error of experimental ΔhdrABC biomass measurement), a 5 to 10% decrease in biomass in the Δrnf mutant (within the error of experimental Δrnf biomass measurement) (32), and equivalent biomasses between the parent and att::hdrABC* strains. The available data and model predictions suggest that when M. acetivorans is growing on methylotrophic substrates, the role of HdrABC is to bypass Rnf by using electrons from ferredoxin to reduce CoM-S-S-CoB (Fig. 5).

Bottom Line: In Methanosarcina acetivorans, HdrABC expression caused an increased rate of methanogenesis and a decrease in metabolic efficiency on methylotrophic substrates.When acetate was the sole carbon and energy source, neither deletion nor overexpression of HdrABC had an effect on growth or methane production rates.These results suggest that in cells grown on methylated substrates, the cell compensates for energy losses due to expression of HdrABC with an increased rate of substrate turnover and that HdrABC lacks the appropriate electron donor in acetate-grown cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry, Redox Biology Center, University of Nebraska-Lincoln, Lincoln, Nebraska, USA.

No MeSH data available.


Related in: MedlinePlus