Abstract
Glutamate glyoxylate aminotransferase (GGAT) catalyzes the reaction of glutamate and glyoxylate to 2-oxoglutarate and glycine. GGAT plays an essential role in the photorespiratory transamination in the peroxisome. We previously identified a photorespiratory GGAT gene (GGAT1) by analyzing a knockout line of the alanine 2-oxoglutarate aminotransferase (AOAT) -like gene (Igarashi et al. Plant J 33, 975- 2003).
To investigate the function of the GGAT1 gene in amino acid and related metabolisms, we obtained transgenic Arabidopsis plants over-expressing GGAT1. The transgenic plants had markedly higher free serine and glycine levels. The serine and glycine content clearly correlated with the level of GGAT1 mRNA expression and with the GGAT activity.
Furthermore metabolic profiling by GC-MS analysis indicated that GGAT1 over-expression plants accumulate many kinds of metabolite including unidentified peaks. These results suggest that the existence of the new metabolic pathway related photorespiration.
