Tetrahydromethanopterin-dependent methanogenesis from non-physiological C1 donors in Methanobacterium thermoautotrophicum.
Methanogenesis from the non-physiological C1 donors thioproline, thiazolidine, hexamethylenetetramine, formaldehyde (HCHO), and HOCH2-S-coenzyme M (CoM) was catalyzed by cell extracts of Methanobacterium thermoautotrophicum under a hydrogen atmosphere. Tetrahydromethanopterin (H4MPT) and HS-CoM were required in the reaction mixture. The non-physiological compounds were found to be in chemical equilibrium with HCHO, which has been shown to react spontaneously with H4MPT to form methylene-H4MPT, an intermediate of the methanogenic pathway at the formaldehyde level of oxidation. Highfield (360 MHZ) 1H and 13C nuclear magnetic resonance studies performed on the interaction between HCHO and HS-CoM showed that these compounds are in equilibrium with HOCH2-S-CoM and that the equilibrium is pH dependent. When methanogenesis from the non-physiological donors was followed under a nitrogen atmosphere, the C1 moiety from each compound underwent a disproportionation, forming methenyl-H4MPT+ and methane. The compounds tested served as substrates for the enzymatic synthesis of methenyl-H4MPT+.
D002244:Carbon / Q000378:metabolism; D019605:Euryarchaeota / Q000378:metabolism*; D005557:Formaldehyde / Q000378:metabolism; D006859:Hydrogen / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008697:Methane / Q000378:metabolism*; D009584:Nitrogen / Q000494:pharmacology; D011622:Pterins / Q000378:metabolism*
D011622:Pterins; D005557:Formaldehyde; D002244:Carbon; D006859:Hydrogen; C042416:5,6,7,8-tetrahydromethanopterin; D009584:Nitrogen; D008697:Methane