Effect of L-glutamate on 2-oxoglutarate decarboxylase in Euglena gracilis.
The effect of tricarboxylic acid-cycle intermediates and related compounds on 2-oxoglutarate decarboxylase activity was investigated. The addition of L-glutamate to Euglena cells grown on glucose/(NH4)2SO4 medium resulted in an increase in 2-oxoglutarate decarboxylase activity, which was abolished by the simultaneous addition of cycloheximide. Immunochemical titration, immunoblot analysis and labelling in vivo with antibody raised against 2-oxoglutarate decarboxylase showed that the increase in 2-oxoglutarate decarboxylase activity was due to synthesis of new protein and not to activation of pre-existing protein. The experimental results reported here demonstrate that L-glutamate is assimilated by the pathway, via 2-oxoglutarate, that consists of L-glutamate-oxaloacetate aminotransferase, 2-oxoglutarate decarboxylase and succinate semialdehyde dehydrogenase, rather than by the gamma-aminobutyrate shunt, consisting of L-glutamate decarboxylase and gamma-aminobutyrate aminotransferase.
Department of Food and Nutrition, Kinki University, Nara, Japan.
S
S
Shigeoka
T
T
Hanaoka
N
N
Kishi
Y
Y
Nakano
D000818:Animals; D015153:Blotting, Western; D002262:Carboxy-Lyases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D003513:Cycloheximide / Q000494:pharmacology; D005056:Euglena gracilis / Q000201:enzymology*; D005971:Glutamates / Q000494:pharmacology*; D018698:Glutamic Acid; D007150:Immunohistochemistry; D008715:Methionine / Q000378:metabolism; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000187:drug effects; D014233:Tricarboxylic Acids / Q000378:metabolism
D005971:Glutamates; D012333:RNA, Messenger; D014233:Tricarboxylic Acids; D018698:Glutamic Acid; D003513:Cycloheximide; D008715:Methionine; D002262:Carboxy-Lyases; C021474:2-oxoglutarate decarboxylase