Plasma membrane N-glycoproteome analysis of wheat seedling leaves under drought stress

N-linked glycoproteome analysis reveals central glycosylated proteins involved in response to wheat yellow mosaic virus in wheat

Glycosylation is an important proteins post-translational modification and is involved in protein folding, stability and enzymatic activity, which plays a crucial role in regulating protein function in plants. Here, we report for the first time on the changes of N-glycoproteome in wheat response to wheat yellow mosaic virus (WYMV) infection. Quantitative analyses of N-linked glycoproteome were performed in wheat without and with WYMV infection by ZIC-HILIC enrichment method combined with LC-MS/MS. Altogether 1160 N-glycopeptides and 971 N-glycosylated sites corresponding to 734 N-glycoproteins were identified, of which 64 N-glycopeptides and 64 N-glycosylated sites in 60 N-glycoproteins were significantly differentially expressed. Two conserved typical N-glycosylation motifs N-X-T and N-X-S and a nontypical motifs N-X-C were enriched in wheat. Gene Ontology analysis showed that most differentially expressed proteins were mainly enriched in metabolic process, catalytic activity and response to stress. Kyoto Encyclopedia of Genes and Genomes analysis indicated that two significantly changed glycoproteins were specifically related to plant-pathogen interaction. Furthermore, we found that over-expression of TaCERK reduced WYMV accumulation. Glycosylation site mutation further suggested that N-glycosylation of TaCERK could regulate wheat resistance to WYMV. This study provides a new insight for the regulation of protein N-glycosylation in defense response of plant.

N-glycosylomic analysis provides new insight into the molecular mechanism of firmness of fish fillet

Post-translational protein modification affects muscle physiochemistry. To understand the roles of N-glycosylation in this process, the muscle N-glycoproteomes of crisp grass carp (CGC) and ordinary grass carp (GC) were analyzed and compared. We identified 325 N-glycosylated sites with the NxT motif, classified 177 proteins, and identified 10 upregulated and 19 downregulated differentially glycosylated proteins (DGPs). Gene Ontology and Kyoto Encyclopedia of Genes and Genomes annotations revealed that these DGPs participate in myogenesis, extracellular matrix content formation, and muscle function. The DGPs partially accounted for the molecular mechanisms associated with the relatively smaller fiber diameter and higher collagen content observed in CGC. Though the DGPs diverged from the identified differentially phosphorylated proteins and differentially expressed proteins detected in previous study, they all shared similar metabolic and signaling pathways. Thus, they might independently alter fish muscle texture. Overall, the present study provides novel insights into the mechanisms underlying fillet quality.

N-glycoproteins in Plant Cell Walls: A Survey

Cell walls are an extracellular compartment specific to plant cells, which are not found in animal cells. Their composition varies between cell types, plant species, and physiological states. They are composed of a great diversity of polymers, i.e., polysaccharides, proteins, and lignins. Cell wall proteins (CWPs) are major players involved in the plasticity of cell walls which support cell growth and differentiation, as well as adaptation to environmental changes. In order to reach the extracellular space, CWPs are transported through the secretory pathway where they may undergo post-translational modifications, including N-glycosylations on the Asn residues in specific motifs (Asn-X-Ser/Thr-X, with X≠Pro). This review aims at providing a survey of the present knowledge related to cell wall N-glycoproteins with (i) an overview of the experimental workflows, (ii) a selection of relevant articles dedicated to N-glycoproteomics, (iii) a description of the diversity of N-glycans, and (iv) a focus on the importance of N-glycans for CWP structure and/or function.

Crop Proteomics under Abiotic Stress: From Data to Insights

Food security is a major challenge in the present world due to erratic weather and climatic changes. Environmental stress negatively affects plant growth and development which leads to reduced crop yields. Technological advancements have caused remarkable improvements in crop-breeding programs. Proteins have an indispensable role in developing stress resilience and tolerance in crops. Genomic and biotechnological advancements have made the process of crop improvement more accurate and targeted. Proteomic studies provide the information required for such targeted approaches. The crosstalk among cellular components is being analyzed by subcellular proteomics. Additionally, the functional diversity of proteins is being unraveled by post-translational modifications during abiotic stress. The exploration of precise cellular responses and the networking among different cellular organelles help in the prediction of signaling pathways and protein-protein interactions. High-throughput mass-spectrometry-based protein studies are now possible due to incremental advancements in mass-spectrometry techniques, sample protocols, and bioinformatic tools as well as the increasing availability of plant genome sequence information for multiple species. In this review, the key role of proteomic analysis in identifying the abiotic-stress-responsive mechanisms in various crops was summarized. The development and availability of advanced computational tools were discussed in detail. The highly variable protein responses among different crops have provided a wide avenue for molecular-marker-assisted genetic buildup studies to develop smart, high-yielding, and stress-tolerant varieties to cope with food-security challenges.

Protein glycosylation changes during systemic acquired resistance in Arabidopsis thaliana

N-glycosylation, an important post-translational modification of proteins in all eukaryotes, has been clearly shown to be involved in numerous diseases in mammalian systems. In contrast, little is known regarding the role of protein N-glycosylation in plant defensive responses to pathogen infection. We identified, for the first time, glycoproteins related to systemic acquired resistance (SAR) in an Arabidopsis thaliana model, using a glycoproteomics platform based on high-resolution mass spectrometry. 407 glycosylation sites corresponding to 378 glycopeptides and 273 unique glycoproteins were identified. 65 significantly changed glycoproteins with 80 N-glycosylation sites were detected in systemic leaves of SAR-induced plants, including numerous GDSL-like lipases, thioglucoside glucohydrolases, kinases, and glycosidases. Functional enrichment analysis revealed that significantly changed glycoproteins were involved mainly in N-glycan biosynthesis and degradation, phenylpropanoid biosynthesis, cutin and wax biosynthesis, and plant-pathogen interactions. Comparative analysis of glycoproteomics and proteomics data indicated that glycoproteomics analysis is an efficient method for screening proteins associated with SAR. The present findings clarify glycosylation status and sites of A. thaliana proteins, and will facilitate further research on roles of glycoproteins in SAR induction.