Dynamics of nitration during dark-induced leaf senescence in Arabidopsis reveals proteins modified by tryptophan nitration

Peroxynitrite fine-tunes the nitro-oxidative environment during dark-induced leaf senescence in Arabidopsis for selective nitrative modification of bio-targets, including proteins containing tryptophan and tyrosine, and nucleic acids. Nitric oxide (NO) is a critical molecule that links plant development with stress responses. Herein, new insights into the role of NO metabolism during leaf senescence in Arabidopsis are presented. A gradual decrease in NO emission accompanied dark-induced leaf senescence (DILS), and a transient wave of peroxynitrite (ONOO-) formation was detected by day 3 of DILS. The boosted ONOO- did not promote tryptophan (Trp) nitration, while the pool of 6-nitroTrp-containing proteins was depleted as senescence progressed. Immunoprecipitation combined with mass spectrometry was used to identify 63 and 4 characteristic 6-nitroTrp-containing proteins in control and individually darkened leaves, respectively. The potential in vivo targets of Trp nitration were mainly related to protein biosynthesis and carbohydrate metabolism. In contrast, nitration of tyrosine-containing proteins was intensified 2-fold on day 3 of DILS. Also, nitrative modification of RNA and DNA increased significantly on days 3 and 7 of DILS, respectively. Taken together, ONOO- can be considered a novel pro-senescence regulator that fine-tunes the redox environment for selective bio-target nitration. Thus, DILS-triggered nitrative changes at RNA and protein levels promote developmental shifts during the plant's lifespan and temporal adjustment in plant metabolism under suboptimal environmental conditions.

Automated summary

Peroxynitrite plays a crucial role in regulating the nitro-oxidative environment during dark-induced leaf senescence in Arabidopsis. It selectively modifies bio-targets including proteins and nucleic acids. The formation of peroxynitrite coincides with the decrease in nitric oxide emission during leaf senescence. Different amino acids and nucleotides in proteins and nucleic acids are nitration targets of peroxynitrite, and this modification has a significant impact on protein biosynthesis and carbohydrate metabolism.