Solid 13C CPMAS NMR spectroscopy studies of biosynthesis in whole cells of Methanosphaera stadtmanae.

Whole cells of Methanosphaera stadtmanae were grown in media containing [13C]CO2, [2-13C]acetate, [1-13C]acetate, [3-13C]serine and [1-13C]formate. The label incorporation was determined using solid state 13C CPMAS NMR spectroscopy. The incorporation of serine hydroxymethyl carbon into the purine rings of nucleic acids and most probably the methyl group of thymine is demonstrated. The one carbon atom pathway shown in our previous work is operative in the biosynthesis of purines and pyrimidines. In addition, these studies clearly identified signals not observed in solution NMR spectroscopy and revealed an important pathway not previously known. The reversibility of formyl-containing one carbon atom carriers is demonstrated. The pattern of labeled carbon atoms in sugars confirms the biosynthetic route from pyruvate, which is formed from acetic acid and carbon dioxide. Finally, a preliminary lipid assignment is indicated. The solid state 13C CPMAS NMR of these intact cells proved to be a facile method to follow specific pathways.