Carbohydrate and amino acid metabolism in Tuber borchii mycelium during glucose utilization: a (13)C NMR study.
The metabolism of [1-13C]glucose in the vegetative mycelium of the ectomycorrhizal ascomycete Tuber borchii was studied in order to characterize the biochemical pathways for the assimilation of glucose and amino acid biosynthesis. The pathways were characterized using nuclear magnetic resonance spectroscopy in conjunction with [1-13C]glucose labeling. The enzymes of mannitol cycle and ammonium assimilation were also evaluated. The majority of the 13C label was incorporated into mannitol and this polyol was formed via a direct route from absorbed glucose. Amino acid biosynthesis was also an important sink of assimilated carbon and 13C was mainly incorporated into alanine and glutamate. From this intramolecular 13C enrichment, it is concluded that pyruvate, arising from [1-13C]glucose catabolism, was used by alanine aminotransferase, pyruvate dehydrogenase and pyruvate carboxylase before entering the Krebs cycle. The transfer of 13C-labeled mycelium on [12C]glucose showed that mannitol, alanine, and glutamate carbon were used to synthesize glutamine and arginine that likely play a storage role.
Ceccaroli
Paola
P
Istituto di Chimica Biologica "Giorgio Fornaini," Università degli Studi di Urbino, Via A Saffi, 2, 61029 (PU), Urbino, Italy. p.ceccaroli@uniurb.it
Saltarelli
Roberta
R
Cesari
Paola
P
Pierleoni
Raffaella
R
Sacconi
Cinzia
C
Vallorani
Luciana
L
Rubini
Patrice
P
Stocchi
Vilberto
V
Martin
Francis
F
D000596:Amino Acids / Q000096:biosynthesis / Q000378:metabolism*; D001203:Ascomycota / Q000254:growth & development / Q000378:metabolism*; D050260:Carbohydrate Metabolism; D003470:Culture Media; D005947:Glucose / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008353:Mannitol / Q000378:metabolism; D025282:Mycelium / Q000378:metabolism*; D013194:Staining and Labeling
D000596:Amino Acids; D003470:Culture Media; D008353:Mannitol; D005947:Glucose