A new insight to explore the regulation between S ‐nitrosylation and N ‐glycosylation

Nitric oxide ( NO ) is a signal molecule in plants and animals. Arabidopsis GSNO reductase1 (At GSNOR 1) catalyzes metabolism of S ‐nitrosoglutathione ( GSNO ) which is a major biologically active NO species. The GSNOR 1 loss‐of‐function mutant gsnor1‐3 overaccumulates GSNO with inherent high S ‐nitrosylation level and resistance to the oxidative stress inducer paraquat (1,1′‐dimethyl‐4,4′‐bipyridinium dichloride). Here, we report the characterization of dgl1‐3 as a genetic suppressor of gsnor1‐3 . DGL 1 encodes a subunit of the oligosaccharyltransferse ( OST ) complex which catalyzes the formation of N ‐glycosidic bonds in N ‐glycosylation. The fact that dgl1‐3 repressed the paraquat resistance of gsnor1‐3 meanwhile gsnor1‐3 rescued the embryo‐lethal and post‐embryonic development defect of dgl1‐3 reminded us the possibility that S ‐nitrosylation and N ‐glycosylation crosstalk with each other through co‐substrates. By enriching glycoproteins in gsnor1‐3 and mass spectrometry analysis, TGG 2 (thioglucoside glucohydrolase2) was identified as one of co‐substrates with high degradation rate and elevated N ‐glycosylation level in gsnor1‐3 ost3/6 . The S ‐nitrosylation and N ‐glycosylation profiles were also modified in dgl1‐3 and gsnor1‐3 . Thereby, we propose a linkage between S ‐nitrosylation and N ‐glycosylation through co‐substrates.