Interference of Arabidopsis N-Acetylglucosamine-1-P Uridylyltransferase Expression Impairs Protein N-Glycosylation and Induces ABA-Mediated Salt Sensitivity During Seed Germination and Early Seedling Development

Abstract

N-acetylglucosamine (GlcNAc) is the fundamental amino sugar moiety that is essential for protein glycosylation. UDP-GlcNAc, an active form of GlcNAc, is synthesized through the hexosamine biosynthetic pathway (HBP). Arabidopsis N-acetylglucosamine-1-P uridylyltransferases (GlcNAc1pUTs), encoded by GlcNA.UTs, catalyze the last step in the HBP pathway, but their biochemical and molecular functions are less clear. In this study, the GlcNA.UT1 expression was knocked down by the double-stranded RNA interference (dsRNAi) in the glcna.ut2 null mutant background. The RNAi transgenic plants, which are referred to as iU1, displayed the reduced UDP-GlcNAc biosynthesis, altered protein N-glycosylation and induced an unfolded protein response under salt-stressed conditions. Moreover, the iU1 transgenic plants displayed sterility and salt hypersensitivity, including delay of both seed germination and early seedling establishment, which is associated with the induction of ABA biosynthesis and signaling. These salt hypersensitive phenotypes can be rescued by exogenous fluridone, an inhibitor of ABA biosynthesis, and by introducing an ABA-deficient mutant allele nced3 into iU1 transgenic plants. Transcriptomic analyses further supported the upregulated genes that were involved in ABA biosynthesis and signaling networks, and response to salt stress in iU1 plants. Collectively, these data indicated that GlcNAc1pUTs are essential for UDP-GlcNAc biosynthesis, protein N-glycosylation, fertility, and the response of plants to salt stress through ABA signaling pathways during seed germination and early seedling development.

Influence of N-Acetylglucosamine and Melatonin Interaction in Modeling the Photosynthetic Component and Metabolomics of Cucumber under Salinity Stress

“…Defects in N-glycan digestion frequently impact plant development and stress responses, resulting in mortality. The growth improvement of cucumber plants in our study aligned with the findings of Chen et al [54], who reported the exogenous application of GlcNAc conferred tolerance and improved growth of wild-type Arabidopsis seedlings under salt stress conditions. Similarly, Sun et al [55] reported that the GlcNAc treatment enhanced the growth of tomato plants via stimulation of microorganism community structure.…”

Hexosamine biosynthesis and related pathways, protein N-glycosylation and O-GlcNAcylation: their interconnection and role in plants

“…Moreover, the iU1s confer slat hypersensitivity, including delay of seed germination and early seedling establishment, in association with the induction of ABA biosynthesis and its signal networks under salt stress. Furthermore, microarray analysis data support the upregulation of genes involved in ABA (such as NCED3 , ABI5 , and ABCG25 ) and salt stress responses (such as RD29A , RD29B , and DREB2A ) ( Chen et al., 2022 ).…”

“…Therefore, the Atgna / lig mutant fails to convert GlcN6-P to GlcNAc-6P; however, exogenous GlcNAc can be catalyzed by AtGNK to form GlcNAc-6-P, which further enters the HBP to produce UDP-GlcNAc. Similarly, wild-type plants (Col-o) produce more UDP-HexNAc (UDP-GlcNAc and UDP-GalNAc) by exogenous GlcNAc under normal and salt-stressed conditions ( Chen et al., 2022 ). The coexistence of HBP and salvage pathways may finetune the homeostasis of UDP-GlcNAc contents in plants in response to nutrient fluctuations and environmental stimuli.…”

“…As mentioned above, HBP generates UDP-GlcNAc to provide GlcNAc donors and initiate oligosaccharide precursor production on the cytosolic side of the ER. Defects in HBP enzymes may reduce UDP-GlcNAc levels, impair N-linked glycosylation, and alter plant growth under normal ( Wang et al., 2015 ; Xiao et al., 2018 ) or abiotic stress conditions ( Zhang et al., 2009 ; Nozaki et al., 2012 ; Chen et al., 2022 ). Moreover, a complete block of HBP normally leads to lethality ( Chen et al., 2014 ; Vu et al., 2019 ; Jia et al., 2023 ).…”

Inhibition of glycolysis-driven immunosuppression with a nano-assembly enhances response to immune checkpoint blockade therapy in triple negative breast cancer

“…However, it is also noteworthy that even a large UDP-GlcNAc dose at around 0.5 mM could only induce partial recovery of PD-L1 glycosylation levels. This is understood that protein glycosylation in tumor cells is largely sustained by the glycolysis activities both in terms of UDP-GlcNAc precursors 20,23,53,54 and metabolite supply 55,56 including ATP and NADPH, both of which are significantly suppressed by the BAY-876-mediated blockade of glucose uptake. This is also supported by the quantitative analysis on the biochemical changes in 2-NBDG-treated 4T1 cells, which revealed a positive correlation between 2-NBDG dosage and F6P/UDP-GlcNAc levels (Fig.…”