The involvement of glutamate dehydrogenase and glutamine synthetase in ammonia assimilation by the rapidly growing ectomycorrhizal ascomycete, Cenococcum geophilum Fr.

摘要: summary In order to determine significance of the glutamate dehydrogenase pathway and a glutamine synthetase/glutamate synthase cycle in NH4+ assimilation, we followed number different metabolikc parameters (nutrient uptake, free amino acid pools, NH4+-induced accumulation) 15N incorporation into acids rapidly growing Cennoccum geophilum. Arginine was major C. geophilum during its entire growth period. synthesized accumulated very large amounts at beginning rapid phase low nitrogen medium, whole period high immediately after addition NH4+. Therefore, accumulation amount tool; place when external ammonium concentration high. The current data identify four pathways N metabolism geophilum: (1) synthesis, invoking transfer both moieties; (2) formation; (3) transamination with pyruvate yield alanine; (4) oxaloacetate asparate. higher related (alanine aspartate) presence synthetase inhibitor methionine sulphoximine indicates that glutamate, precursor glutamine, formed by insensitive sulphoximine, pathway. Up 40% assimilated terminated amido-N glutamine. These are consistent pivotal role for activity primary assimilation is brought about concurrent GDH GS pathways. geophilunt therefore differs from those operating stationary where flax through than flux