Aspergillus terreus NADP-glutamate dehydrogenase is kinetically distinct from the allosteric enzyme of other Aspergilli.
NADP-Glutamate dehydrogenase (NADP-GDH) located at the interface of carbon and nitrogen metabolism has the potential to dictate fungal carbon flux. NADP-GDH from Aspergillus terreus, itaconate producer and an opportunistic pathogen, was purified to homogeneity using novel reactive dye-affinity resins. The pure enzyme was extensively characterized for its biochemical and kinetic properties and compared with its well studied Aspergillus niger counterpart. The A. terreus NADP-GDH was more stable and showed non-competitive ammonium inhibition with respect to glutamate. It exhibited hyperbolic 2-oxoglutarate saturation albeit with a weak substrate inhibition. This is in contrast to the allosteric nature of the enzyme from other Aspergilli. Differential susceptibility to chymotrypsin is also consistent with the absence of substrate cooperativity and conformational changes associated with A. terreus NADP-GDH. The non-allosteric nature of A. terreus NADP-GDH provides a unique opportunity to assess the contribution of allostery in metabolic regulation.
Choudhury
Rajarshi
R
Biotechnology Group, School of Bioscience and Bioengineering, Indian Institute of Technology Bombay, Mumbai-400076, India.
Punekar
N S
NS
D000494:Allosteric Regulation; D000595:Amino Acid Sequence; D001230:Aspergillus / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D001234:Aspergillus niger / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D005656:Fungal Proteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D018086:Glutamate Dehydrogenase (NADP+) / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D007700:Kinetics; D008969:Molecular Sequence Data; D016415:Sequence Alignment
D005656:Fungal Proteins; D018086:Glutamate Dehydrogenase (NADP+)