title: Loss-of-function of an Arabidopsis NADPH pyrophosphohydrolase, AtNUDX19, impacts on the pyridine nucleotides status and confers photooxidative stress tolerance.
abstract: The levels and redox states of pyridine nucleotides, such as NADP(H), regulate the cellular redox homeostasis, which is crucial for photooxidative stress response in plants. However, how they are controlled is poorly understood. An Arabidopsis Nudix hydrolase, AtNUDX19, was previously identified to have NADPH hydrolytic activity in vitro, suggesting this enzyme to be a regulator of the NADPH status. We herein examined the physiological role of AtNUDX19 using its loss-of-function mutants. NADPH levels were increased in nudx19 mutants under both normal and high light conditions, while NADP+and NAD+levels were decreased. Despite the high redox states of NADP(H), nudx19 mutants exhibited high tolerance to moderate light- or methylviologen-induced photooxidative stresses. This tolerance might be partially attributed to the activation of either or both photosynthesis and the antioxidant system. Furthermore, a microarray analysis suggested the role of ANUDX19 in regulation of the salicylic acid (SA) response in a negative manner. Indeed, nudx19 mutants accumulated SA and showed high sensitivity to the hormone. Our findings demonstrate that ANUDX19 acts as an NADPH pyrophosphohydrolase to modulate cellular levels and redox states of pyridine nucleotides and fine-tunes photooxidative stress response through the regulation of photosynthesis, antioxidant system, and possibly hormonal signaling.
authors.affiliation: Department of Advanced Bioscience, Faculty of Agriculture, Kindai University, 3327-204 Nakamachi, Nara 631-8505, Japan.|Department of Life Science and Biotechnology, Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504, Japan.
authors.forename: Takanori
authors.initials: T
authors.lastname: Maruta
authors.affiliation: Department of Advanced Bioscience, Faculty of Agriculture, Kindai University, 3327-204 Nakamachi, Nara 631-8505, Japan.|Department of Life Science and Biotechnology, Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504, Japan.
authors.forename: Takahisa
authors.initials: T
authors.lastname: Ogawa
authors.affiliation: Department of Advanced Bioscience, Faculty of Agriculture, Kindai University, 3327-204 Nakamachi, Nara 631-8505, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Tsujimura
authors.affiliation: Department of Advanced Bioscience, Faculty of Agriculture, Kindai University, 3327-204 Nakamachi, Nara 631-8505, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Ikemoto
authors.affiliation: Department of Advanced Bioscience, Faculty of Agriculture, Kindai University, 3327-204 Nakamachi, Nara 631-8505, Japan.
authors.forename: Tomofumi
authors.initials: T
authors.lastname: Yoshida
authors.affiliation: Graduate School of Horticulture, Chiba University, 648 Matsudo, Matsudo, Chiba 271-8510, Japan.
authors.forename: Hiro
authors.initials: H
authors.lastname: Takahashi
authors.affiliation: Department of Food and Nutritional Science, College of Bioscience and Biotechnology, Chubu University, 1200 Matsumoto-cho, Kasugai, Aichi 487-8501, Japan (K.Y.).
authors.forename: Kazuya
authors.initials: K
authors.lastname: Yoshimura
authors.affiliation: Department of Advanced Bioscience, Faculty of Agriculture, Kindai University, 3327-204 Nakamachi, Nara 631-8505, Japan.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Shigeoka
mesh_terms: D000222:Adaptation, Physiological / Q000528:radiation effects*; D000975:Antioxidants / Q000378:metabolism; D017360:Arabidopsis / Q000201:enzymology* / Q000502:physiology / Q000528:radiation effects; D002467:Cell Nucleus / Q000378:metabolism / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D008027:Light; D000073658:Loss of Function Mutation / Q000235:genetics*; D009711:Nucleotides / Q000378:metabolism*; D010084:Oxidation-Reduction / Q000528:radiation effects; D018384:Oxidative Stress / Q000528:radiation effects*; D010788:Photosynthesis / Q000528:radiation effects; D010802:Phylogeny; D011725:Pyridines / Q000378:metabolism*; D011755:Pyrophosphatases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020156:Salicylic Acid / Q000378:metabolism; D000096964:Nudix Hydrolases
chemical_list: D000975:Antioxidants; D009711:Nucleotides; D011725:Pyridines; D011755:Pyrophosphatases; D020156:Salicylic Acid; D000096964:Nudix Hydrolases