title: Pathways of Amino Acid Degradation in Nilaparvata lugens (Stål) with Special Reference to Lysine-Ketoglutarate Reductase/Saccharopine Dehydrogenase (LKR/SDH).
abstract: Nilaparvata lugens harbors yeast-like symbionts (YLSs). In present paper, a genome-wide analysis found 115 genes from Ni. lugens and 90 genes from YLSs that were involved in the metabolic degradation of 20 proteinogenic amino acids. These 205 genes encoded for 77 enzymes. Accordingly, the degradation pathways for the 20 amino acids were manually constructed. It is postulated that Ni. lugens can independently degrade fourteen amino acids (threonine, alanine, glycine, serine, aspartate, asparagine, phenylalanine, tyrosine, glutamate, glutamine, proline, histidine, leucine and lysine). Ni. lugens and YLSs enzymes may work collaboratively to break down tryptophan, cysteine, arginine, isoleucine, methionine and valine. We cloned a lysine-ketoglutarate reductase/saccharopine dehydrogenase gene (Nllkr/sdh) that encoded a bifunctional enzyme catalyzing the first two steps of lysine catabolism. Nllkr/sdh is widely expressed in the first through fifth instar nymphs and adults, and is highly expressed in the fat body, ovary and gut in adults. Ingestion of dsNllkr/sdh by nymphs successfully knocked down the target gene, and caused nymphal/adult mortality, shortened nymphal development stage and reduced adult fresh weight. Moreover, Nllkr/sdh knockdown resulted in three defects: wings were shortened and thickened; cuticles were stretched and thinned; and old nymphal cuticles remained on the tips of legs and abdomen and were not completely shed. These data indicate that impaired lysine degradation negatively affects the survival and development of Ni. lugens.
authors.affiliation: State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou 310006, China; Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Pin-Jun
authors.initials: PJ
authors.lastname: Wan
authors.affiliation: State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou 310006, China; Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: San-Yue
authors.initials: SY
authors.lastname: Yuan
authors.affiliation: State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou 310006, China.
authors.forename: Yao-Hua
authors.initials: YH
authors.lastname: Tang
authors.affiliation: State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou 310006, China.
authors.forename: Kai-Long
authors.initials: KL
authors.lastname: Li
authors.affiliation: State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou 310006, China; Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Lu
authors.initials: L
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou 310006, China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Fu
authors.affiliation: Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Guo-Qing
authors.initials: GQ
authors.lastname: Li
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D030801:Animals, Genetically Modified; D006430:Hemiptera / Q000378:metabolism*; D012443:Saccharopine Dehydrogenases / Q000235:genetics / Q000378:metabolism*; D013559:Symbiosis / Q000235:genetics*
chemical_list: D000596:Amino Acids; D012443:Saccharopine Dehydrogenases