Sequence of the GLT1 gene from Saccharomyces cerevisiae reveals the domain structure of yeast glutamate synthase

Glutamate synthase (GOGAT) and glutamine synthetase play a crucial role in ammonium assimilation and glutamate biosynthesis in the yeast Saccharomyces cerevisiae. The GOGAT enzyme has been purified and the GOGAT structural gene (GLT1) has been cloned, showing that this enzyme is a homotrimeric protein with a monomeric size of 199 kDa. We report the GLT1 nucleotide sequence and the amino acid sequence of its deduced protein product. Our results show that there is a high conservation with the corresponding genes of Escherichia coli, Medicago sativa (alfalfa) and Zea mais (maize). Binding domains for glutamine, cofactors (FMN and NADH) and the cysteine clusters (which comprise the iron-sulfur centres) were tentatively identified on the basis of sequence comparison with GOGAT sequences from E. coli, alfalfa and maize.