Glutamate synthase (NADH-GOGAT) is one of several proteins whose expression is either enhanced in, or specific to developing legume root nodules induced by (Brady)Rhizobium infection. This enzyme catalyzes the second committed step in the assimilation of symbiotically fixed nitrogen; the transamidation of 2-oxoglutarate by glutamine to yield two moles of glutamate. We have previously purifed alfalfa root nodule NADH-GOGAT and raised antibodies against this protein. To investigate the regulation of the gene encoding this enzyme, we have isolated a full length cDNA clone for NADH-GOGAT from an alfalfa nodule cDNA library. This 7.5 kb cDNA includes the sequence encoding the mature 210 kd protein (the amino terminus of which has been sequenced), as well as an apparent transit peptide. Northern blots indicate that mRNA levels are developmentally regulated in the nodule, showing a similar pattern to that of previously characterized genes encoding aspartate aminotransferase and phosphoenoylpyruvate carboxylase.
KeywordsAcyl Carrier Protein Inflorescence Meristem Auxin Transport Inhibitor Precocious Germination Globulin Gene
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