Institute of Molecular Physiology and Biotechnology of Plants, University of Bonn, Kirschallee 1, 53115, Bonn, Germany.
Institute of Molecular Physiology and Biotechnology of Plants, University of Bonn, Kirschallee 1, 53115, Bonn, Germany.
Plant Sci. 2020 Mar;292:110389. doi: 10.1016/j.plantsci.2019.110389. Epub 2019 Dec 24.
Nitric oxide (NO) is an intracellular messenger that mediates stress responses. Several plant aldehyde dehydrogenase (ALDH) genes are expressed during abiotic stress conditions to reduce the level of cytotoxic aldehydes. We investigated a possible interference between NO and ALDHs, using the isoform ALDH3H1 of Arabidopsis thaliana as model. The physiological NO donor; S-nitrosoglutathione (GSNO), inhibits ALDH3H1 in a time- and concentration-dependent manner. Mutagenesis and ESI-MS/MS analyses show that all Cys residues of ALDH3H1 are targets of GSNO-mediated S-nitrosation. Chemical labelling indicates that the deactivation is due to the conversion of the catalytic thiol into a catalytically non-active nitrosothiol. GSNO has the same effect on the chloroplastic ALDH3I1, suggesting that susceptibility of the catalytic Cys to NO is a common feature of ALDHs. S-Nitrosation and enzymatic inhibition of ALDH were reverted by reducing agents. Our study proves that the function of ALDHs does not exclusively depend on transcriptional regulation, with stress-induced expression, but may be also susceptible to posttranslational regulation through S-nitrosation. We discuss the potential involvement of S-nitrosoglutathione reductase (GSNOR), binding specific cofactors and reducing partners in a protective system of ALDHs in vivo, which will be experimentally corroborated in our forthcoming study.
一氧化氮（NO）是一种细胞内信使，介导应激反应。几种植物醛脱氢酶（ALDH）基因在非生物胁迫条件下表达，以降低细胞毒性醛的水平。我们使用拟南芥的同工型 ALDH3H1 作为模型，研究了 NO 和 ALDHs 之间可能存在的干扰。生理 NO 供体 S-亚硝基谷胱甘肽（GSNO）以时间和浓度依赖的方式抑制 ALDH3H1。突变和 ESI-MS/MS 分析表明，ALDH3H1 的所有半胱氨酸残基都是 GSNO 介导的 S-亚硝化的靶标。化学标记表明失活是由于催化硫醇转化为催化非活性亚硝基硫醇。GSNO 对叶绿体 ALDH3I1 也有相同的作用，这表明催化半胱氨酸对 NO 的敏感性是 ALDHs 的共同特征。还原剂可使 ALDH 的 S-亚硝基化和酶抑制作用恢复。我们的研究证明，ALDH 的功能不仅取决于转录调控和胁迫诱导表达，还可能易受 S-亚硝基化的翻译后调控。我们讨论了 S-亚硝基谷胱甘肽还原酶（GSNOR）、结合特定辅因子和还原伙伴在体内 ALDH 保护系统中的潜在作用，我们即将进行的研究将对此进行实验验证。
