Project description:Biogenic methane formation, methanogenesis, a key process in the global carbon cycle is the only energy metabolism known to sustain growth of the microorganisms employing it, the methanogenic archaea. All known methanogenic pathways converge at the methane-liberating step where also the terminal electron acceptor of methanogenic respiration, the heterodisulfide of coenzyme M and coenzyme B is formed. Carbon monoxide (CO) utilization of Methanosarcina acetivorans is unique in that the organism can shift from methanogenesis towards acetogenesis. Here, we show that M. acetivorans can dispense of methanogenesis for energy conservation completely. By disrupting the methanogenic pathway through targeted mutagenesis, followed by adaptive evolution, a strain capable of sustained growth by CO-dependent acetogenesis was created. Still, a minute flux through the methane-liberating reaction remained essential, which was attributed to the involvement of the heterodisulfide in at least one essential anabolic reaction. Genomic and proteomic analysis showed that substantial metabolic rewiring had occurred in the strain. Most notably, heterodisulfide reductase, the terminal respiratory oxidoreductase was eliminated to funnel the heterodisulfide towards anabolism. These results suggest that the metabolic flexibility of “methanogenic” archaea is much greater than anticipated and open avenues for probing the mechanism of energetic coupling and the crosstalk between catabolism and anabolism.
Project description:Skyline software was used to analyze 150 target peptides from 83 target proteins, and isotopically labeled peptides were used to normalize the quantitative information, thereby performing relative quantitative analysis of the target peptides and target proteins. By selecting one item, the analysis results indicated that there were certain differences in the expression levels of the target proteins.
Project description:The experiment used Skyline software to analyze 150 target peptides from 83 target proteins. Detailed quantitative information of the target peptides in the samples is provided in Supplementary Tables 1 and 2. Quantitative information was normalized and corrected using isotopically labeled peptides, enabling relative quantitative analysis of the target peptides and target proteins. The analysis results indicate that there are certain differences in the expression levels of the target proteins.