Metabolism of glutamate by Bradyrhizobuim japonicum bacteroids

Journal Article · Fri Mar 31 23:00:00 EST 1989 · Plant Physiology, Supplement; (USA)

OSTI ID:6610135

Salminen, S O; Streeter, J G ^[1]

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1. Ohio State Univ., Wooster (USA)

The authors have previously shown that under microacrophilic conditions B. japonicum USDA 110 bacteroids convert labeled dicarboxylic and amino acids to glutamate (GLU) which is by far the most heavily labeled compound. In searching for an explanation for the GLU accumulation we suspected that {alpha}-ketoglutarate dehydrogenase (AKGDH) activity might be low. The level of activity in the bacteriods was comparable to that found in cultured bacteria. The enzyme was inhibited 42% by 0.1 mM NADH. Thus high endogenous NAD(P)H levels could lead to {alpha}-ketoglutarate being channeled to GLU. Breakdown of GLU could involve the {gamma}-aminobutyrate (GAB) shunt. However, GAB was not significantly labeled when {sup 14}C-GLU was supplied to bacteroids. Unlabeled GAB or GAB amino-transferase inhibitors did not trap {sup 14}C in GAB. Assays of soluble protein from bacteroids showed no GLU decarboxylase activity. The lack of GAB shunt activity would complement the regulation of AKGDH; if the shunt were active, the regulation of AKGDH would serve no purpose, because the net effect of both pathways is the conversion of GLU to succinate.

• OSTI ID: 6610135
• Journal Information: Plant Physiology, Supplement; (USA), Journal Name: Plant Physiology, Supplement; (USA) Vol. 89:4; ISSN PPYSA; ISSN 0079-2241
• Country of Publication: United States
• Language: English

Related Subjects

550501* -- Metabolism-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AMINO ACIDS
BACTERIA
BIOLOGICAL PATHWAYS
CARBON 14 COMPOUNDS
CARBOXYLIC ACIDS
ENZYME ACTIVITY
ENZYME INHIBITORS
ENZYMES
GLUTAMIC ACID
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
METABOLISM
MICROORGANISMS
NITROGEN FIXATION
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXIDOREDUCTASES
RHIZOBIUM
TRACER TECHNIQUES