Organization and Structure of Ferredoxin-Dependent Glutamate Synthase Gene and Intracellular Localization of the Enzyme Protein in Rice Plants

A 5822bp long cDNA clone encoding the full length ferredoxin-dependent glutamate synthase (Fd-GOGAT; EC 1.4.7.1) protein was isolated from roots of rice (Oryza sativa L. cv. Sasanishiki). Its sequence was identical to those of partial cDNAs for Fd-GOGAT from green leaves and shoots of rice. The predicted open reading frame (4848bp) encodes a 1616 amino acid protein with a molecular mass of 175034 Da that includes a 96-amino acid presequence. The combined nucleotide sequence of genomic clones for Fd-GOGAT isolated from rice was 20899 bp long and contained an entire structural gene, a 5672bp 5’-upstream region from the first methionine and a 779bp 3’-downstream region from the stop codon. The predicted transcribed region (15.4kb) consisted of 33 exons separated by 32 introns. The evolution among diverse GOGAT proteins, expression of Fd-GOGAT gene and intracellular localization of this protein in rice roots are also described.