Abstract
Glutamate glyoxylate aminotransferase (GGAT) catalyzes the reaction of glutamate and glyoxylate to 2-oxoglutalate and glycine. GGAT has essential roles for the transamination to photorespiratory cycles in peroxisome. We had identified photorespiratory GGAT gene by analyzing the knockout line of alanine 2-oxoglutarate aminotransferase (AOAT) -like gene (Igarashi et al. Plant J 33, 975- 2003).
To better understand the function of GGAT1 gene on the amino acid metabolisms, we obtained many GGAT1 overexpression lines (OE) that had various levels of GGAT1 mRNA. The levels of free serine were increased drastically in transgenic Arabidopsis plants (maximum level of the OE was 20-times higher than that of the non-transgenic plants). There is a clearly correlation between the level of serine contents, the level of GGAT1 mRNA expressions and GGAT activities. These results suggested that photorespiratory transamination would participate in regulation of the amino acid metabolisms.
