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Molecular cloning, characterization and regulation of two different NADH-glutamate synthase cDNAs in bean nodules
- NADH-dependent glutamate synthase (NADH-GOGAT) is a key enzyme in primary ammonia assimilation in Phaseolus vulgaris nodules. Two different types of cDNA clones of PvNADH-GOGAT were isolated from the nodule cDNA libraries. The full-length cDNA clones of PvNADH-GOGAT-I (7.4 kb) and PvNADH-GOGAT-II (7.0 kb), which displayed an 83% homology between them, were isolated using cDNA library screening, 'cDNA library walking' and RT-PCR amplification. Southern analysis employing specific 5' cDNA probes derived from PvNADH-GOGAT-I and PvNADH-GOGAT-II indicated the existence of a single copy of each gene in the bean genome. Both these proteins contain ~100 amino acid sequences theoretically addressing each isoenzyme to different subcellular compartments. RT-PCR analysis indicated that PvNADH-GOGAT-II expression is higher than PvNADH-GOGAT-I during nodule development. Expression analysis by RT-PCR also revealed that both of these genes are differentially regulated by sucrose. On the other hand, the expression of PvNADH-GOGAT-I, but not PvNADH-GOGAT-II, was inhibited with nitrogen compounds. In situ hybridization and promoter expression analyses demonstrated that the NADH-GOGAT-I and -II genes are differentially expressed in bean root and nodule tissues. In silico analyses of the NADH-GOGAT promoters revealed the presence of potential cis elements in them that could mediate differential tissue-specific, and sugar and amino acid responsive expression of these genes.
Blanco, Lourdes , Reddy, Pallavolu M. , Silvente, Sonia , Bucciarelli, Bruna , Khandual, Sanghamitra , Alvarado-Affantranger, Xochitl , Sanchez, Federico , Miller, Susan , Vance, Carroll , Lara-Flores, Miguel
Phaseolus vulgaris , beans , root nodules , glutamate synthase (NADH) , molecular cloning , complementary DNA , promoter regions , gene expression regulation , nitrogen fixation , Rhizobium etli , amino acid sequences
- Includes references
- Plant, cell & environment 2008 Apr., v. 31, no. 4
- Oxford, UK : Blackwell Publishing Ltd
Journal Articles, USDA Authors, Peer-Reviewed
- Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.