蛋白S-亚硝基化,其定义为一氧化氮(NO)与半胱氨酸残基的巯基共价连接,已知在植物发育和胁迫响应中起关键作用。NO促进幼苗的光形态发生,并且NO的发射被光增强。然而,蛋白质S-亚硝基化在植物光形态发生中的功能尚不清楚。E3连接酶组成光形态发生1(COP1)和转录因子细长下胚型5(HY5)拮抗调节幼苗光形态发生。COP1通过靶向26S蛋白酶体降解的光形态发生启动子如HY5来抑制植物的光形态发生。这里,我们报道COP1在体外是S-亚硝基化的。质谱分析显示,两个进化上保守的残基,COP1的WD40结构域中的半胱氨酸425和半胱氨酸607是S-亚硝基化的。S-亚硝基化谷胱甘肽(GSNO)是蛋白质S-亚硝基化的重要生理NO供体。拟南芥(拟南芥)gsnor1-3突变体,积累更高水平的GSNO,积累了比野生型(WT)更高的HY5水平,表明COP1活性被抑制。蛋白质S-亚硝基化可以在植物中被硫氧还蛋白-h5(TRXh5)逆转。的确,COP1与TRXh5及其紧密同源物TRXh3直接相互作用。此外,过氧化氢酶3(CAT3)充当转硝基转移酶,将NO转移到其靶蛋白如GSNO还原酶(GSNOR)。我们发现CAT3与植物中的COP1相互作用。一起来看,我们的数据表明,COP1的活性可能被NO通过S-亚硝基化抑制,以促进HY5的积累和光形态发生。
Protein S-nitrosylation, which is defined by the covalent attachment of nitric oxide (NO) to the thiol group of cysteine residues, is known to play critical roles in plant development and stress responses. NO promotes seedling
photomorphogenesis and NO emission is enhanced by light. However, the function of protein S-nitrosylation in plant
photomorphogenesis is largely unknown. E3 ligase CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1) and transcription factor ELONGATED HYPOCOTYL 5 (HY5) antagonistically regulate seedling
photomorphogenesis. COP1 inhibits plant
photomorphogenesis by targeting photomorphogenic promoters like HY5 for 26S proteasome degradation. Here, we report that COP1 is S-nitrosylated in vitro. Mass spectrometry analyses revealed that two evolutionarily well conserved residues, cysteine 425 and cysteine 607, in the WD40 domain of COP1 are S-nitrosylated. S-nitrosylated glutathione (GSNO) is an important physiological NO donor for protein S-nitrosylation. The Arabidopsis (Arabidopsis thaliana) gsnor1-3 mutant, which accumulates higher level of GSNO, accumulated higher HY5 levels than wildtype (WT), indicating that COP1 activity is inhibited. Protein S-nitrosylation can be reversed by Thioredoxin-h5 (TRXh5) in plants. Indeed, COP1 interacts directly with TRXh5 and its close homolog TRXh3. Moreover, catalase 3 (CAT3) acts as a transnitrosylase that transfers NO to its target proteins like GSNO reductase (GSNOR). We found that CAT3 interacts with COP1 in plants. Taken together, our data indicate that the activity of COP1 is likely inhibited by NO via S-nitrosylation to promote the accumulation of HY5 and
photomorphogenesis.