title: Biosynthetic pathways of the osmolytes N epsilon-acetyl-beta-lysine, beta-glutamine, and betaine in Methanohalophilus strain FDF1 suggested by nuclear magnetic resonance analyses.
abstract: Methanohalophilus strain FDF1 synthesizes beta-glutamine, betaine, and N epsilon-acetyl-beta-lysine as osmoprotective agents when the cells are grown in high external concentrations of NaCl. Nuclear magnetic resonance spectroscopic analyses of 13CH3OH-12CO2 label incorporation by the cells provide information on the biosynthetic pathways of these organic osmolytes. The labeling studies indicate that Methanohalophilus strain FDF1 produces glutamate and beta-glutamine via a partial oxidative Krebs pathway. 13C labeling of betaine is consistent with methylation of glycine generated from serine (via serine hydroxymethyltransferase). The labeling pattern for N epsilon-acetyl-beta-lysine is consistent with the synthesis of its precursor alpha-lysine occurring by the diaminopimelate pathway in these cells.
authors.affiliation: Department of Chemistry, Boston College, Chestnut Hill, Massachusetts 02167.
authors.forename: M F
authors.initials: MF
authors.lastname: Roberts
authors.forename: M C
authors.initials: MC
authors.lastname: Lai
authors.forename: R P
authors.initials: RP
authors.lastname: Gunsalus
mesh_terms: D001622:Betaine / Q000378:metabolism*; D019605:Euryarchaeota / Q000378:metabolism*; D005973:Glutamine / Q000096:biosynthesis*; D008239:Lysine / Q000031:analogs & derivatives* / Q000096:biosynthesis; D009682:Magnetic Resonance Spectroscopy
chemical_list: D005973:Glutamine; C075812:N'-acetyl-beta-lysine; D001622:Betaine; D008239:Lysine