Abstract
Nudix hydrolases are widely distributed among eukaryotes, bacteria, archaea, and viruses. They are divided into subfamilies based on their major substrates: ribo- and deoxy-nucleoside triphophates, ADP-ribose, NADH, CoA, and dinucleoside polyphosphates. Previously, we have demonstrated the molecular characterization of cytosolic Nudix hydrolases (J. Biol. Chem. 2005 280: 25277-83, Plant Cell Physiol. 2007, 48: 1438-49). Here we report the comprehensive analysis of chloroplastic AtNUDXs (AtNUDX19~24, 26, and 27). Among the chloroplastic AtNUDXs, AtNUDX19 and 23 showed NAD(P)H and FAD pyrophosphatase activities, respectively. AtNUDX26 and 27 acted on diadenosine polyphosphates. These results suggest that AtNUDX19 and 23 are pertinent to the regulation of diverse metabolic pathways, such as photosynthesis, redox reactions, and light sensing via hydrolyzation of NAD(P)H and FAD in chloroplasts. We are progressing toward to analyze their physiological functions using knock-out and overexpressing mutants.
