Endoplasmic reticulum adenylate transporter activity affects amino acid metabolism under photorespiratory conditions  

作　　者：Jieni Li Yuxin Song Xin Luan Yajun Gou Tao Xie Yu Hong Na Liu Yao Su Xueli Fu Tianxiu Zhong Shu Chen Yuexiong Zhang Gang Qin Xiang-Qian Zhang 

机构地区：[1]Department of Horticulture,College of Agricultural and Biological Engineering,Foshan University,Foshan 528000,Guangdong,China [2]Rice Research Institute,Guangxi Academy of Agricultural Sciences/Guangxi Key Laboratory of Rice Genetics and Breeding,Nanning 530007,Guangxi,China [3]Rice Research Institute,Guangdong Academy of Agricultural Sciences,Guangzhou 510640,Guangdong,China [4]College of Forestry and Landscape Architecture,South China Agricultural University,Guangzhou 510642,Guangdong,China

出　　处：《The Crop Journal》2024年第6期1633-1644,共12页作物学报（英文版）

基　　金：supported by the National Natural Science Foundation of China (31671594);Guangdong Basic and Applied Basic Research Foundation (2024A1515011098,2021A1515012482).

摘　　要：The involvement of the endoplasmic reticulum(ER)-localized adenylate transporter1(ER-ANT1)in photorespiratory metabolism has been established,yet its precise physiological function remains uncertain.Rice er-ant1 mutant plants grown in ambient air exhibited stunted growth and substantial alterations in amino acid metabolites,but recovery in a high CO_(2) condition(1.5%).We show that the absence of ERANT1 hindered the breakdown of glycine without affecting its synthesis,leading to a substantial accumulation of glycine,diminished levels of serine,and depleted reserves of glutamate and alanine.Intriguingly,the er-ant1 plants grown in high CO_(2) and later exposed to ambient air displayed reduced serine levels within 12 h,yet they accumulated serine a week after transferring to ambient air due to induced phosphorylated serine synthesis pathways.Furthermore,knockout of ER-ANT1 marginally impacted the transcription of genes governing core enzymes in photorespiration,but notably upregulated BOU expression that encodes a putative mitochondrial glutamate transporter and AGAT1 that encodes an alanine:glyoxylate aminotransferase gene.Surprisingly,AGAT1,an ER-localized protein,exhibited higher activity that correlates with the decreased alanine levels observed in the er-ant1 mutant.Lack of ER-ANT1 activity also led to a significantly elevated NADH/NAD+ratio that potentially hinders the glycine-to-serine conversion process.This supports the hypothesis that the lack of ER-ANT1-induced limitation of ATP usage might inhibit GDC activity by modulating the NADH/NAD+ratio.Moreover,non-proteinogenic amino acids,including β-alanine and γ-aminobutyrate(GABA),underwent significant alterations,even under high CO_(2) conditions in the er-ant mutant,implying additional non-photorespiration roles of ER-ANT1.Taken together,our results indicate that ER-localized ER-ANT1 plays a crucial role in amino acid metabolism during photorespiration.

关 键 词：Endoplasmic reticulum PHOTORESPIRATION Amino acid Glutamate/alanine aminotransferase ER-ANT1 

分 类 号：S511[农业科学—作物学]