Abstract
PII protein in bacteria is a sensor for 2-oxoglutarate and a transmitter for glutamine (Gln) signaling. In higher plant, Gln could also be a signaling molecule, but nothing is clearly understood about its molecular mechanism. We searched for proteins that interact with rice PII-like protein with a yeast two-hybrid system using a rice cDNA library. The PII like protein interacted with N-acetylglutamate kinase 1 (OsNAGK1) and the PII-like protein itself in rice. Both the PII-like protein and OsNAGK1 are located in chloroplasts in rice leaf blades. Genes for PII-like protein and OsNAGK1 were coordinately expressed in rice leaf blades during the life span. Microarray analysis successfully identified several genes, either up- or down-regulated, in leaf blades of the RNAi-mediated OsGlnB-knockdown rice. The decrease in free arginine content was observed in leaf blades of the OsGlnB-knockdown rice, although the contents of total amino acids were identical between these plants.
