Tyr152 plays a central role in the catalysis of 1-aminocyclopropane-1-carboxylate synthase

The Potential Diagnostic Utility of SMAD4 and ACCS in the Context of Inflammation in Type 2 Diabetes Mellitus Patients

The search for new parameters for the prediction of type 2 diabetes mellitus (T2DM) or its harmful consequences remains an important field of study. Depending on the low-grade inflammatory nature of diabetes, we investigated three proteins in T2DM patients: 1-aminocyclopropane-1-carboxylate synthase (ACCS), granulocyte-colony-stimulating factor (G-CSF), and Sma Mothers Against Decapentaplegic homolog-4 (SMAD4). In brief, sixty T2DM and thirty healthy controls had their serum levels of ACCS, G-CSF, SMAD4, and insulin tested using the ELISA method. The insulin resistance (IR) parameter (HOMA2IR), beta-cell function percentage (HOMA2%B), and insulin sensitivity (HOMA2%S) were all determined by the Homeostasis Model Assessment-2 (HOMA2) calculator. The predictability of these protein levels was investigated by neural network (NN) analysis and was associated with measures of IR. Based on the results, ACCS, G-CSF, and SMAD4 increased significantly in the T2DM group compared with the controls. Their levels depend on IR status and inflammation. The multivariate GLM indicated the independence of the levels of these proteins on the covariates or drugs taken. The receiver operating characteristic area under the curve (AUC) for the prediction of T2DM using NN analysis is 0.902, with a sensitivity of 71.4% and a specificity of 93.8%. The network predicts T2DM well with predicted pseudoprobabilities over 0.5. The model's predictive capability (normalized importance) revealed that ACCS is the best model (100%) for the prediction of T2DM, followed by G-CSF (75.5%) and SMAD4 (69.6%). It can be concluded that ACCS, G-CSF, and SMAD4 are important proteins in T2DM prediction, and their increase is associated with the presence of inflammation.

Domain Swapping between AtACS7 and PpACL1 Results in Chimeric ACS-like Proteins with ACS or Cβ-S Lyase Single Enzymatic Activity

The gaseous hormone ethylene plays a pivotal role in plant growth and development. In seed plants, the key rate-limiting enzyme that controls ethylene biosynthesis is ACC synthase (ACS). ACS has, for a long time, been believed to be a single-activity enzyme until we recently discovered that it also possesses C_β-S lyase (CSL) activity. This discovery raises fundamental questions regarding the biological significance of the dual enzymatic activities of ACS. To address these issues, it is highly necessary to obtain ACS mutants with either ACS or CSL single activity. Here, domain swapping between Arabidopsis AtACS7 and moss CSL PpACL1 were performed. Enzymatic activity assays of the constructed chimeras revealed that, R10, which was produced by replacing AtACS7 box 6 with that of PpACL1, lost ACS but retained CSL activity, whereas R12 generated by box 4 substitution lost CSL and only had ACS activity. The activities of both chimeric proteins were compared with previously obtained single-activity mutants including R6, AtACS7^Q98A, and AtACS7^D245N. All the results provided new insights into the key residues required for ACS and CSL activities of AtACS7 and laid an important foundation for further in-depth study of the biological functions of its dual enzymatic activities.

Plant-soil-microbes: A tripartite interaction for nutrient acquisition and better plant growth for sustainable agricultural practices

Plants can achieve their proper growth and development with the help of microorganisms associated with them. Plant-associated microbes convert the unavailable nutrients to available form and make them useful for plants. Besides nutrient acquisition, soil microbes also inhibit the pathogens that cause harm to plant growth and induces defense response. Due to the beneficial activities of soil nutrient-microbe-plant interactions, it is necessary to study more on this topic and develop microbial inoculant technology in the agricultural field for better crop improvement. The soil microbes can be engineered, and plant growth-promoting rhizobacteria (PGPR) and plant growth-promoting bacteria (PGPB) technology can be developed as well, as its application can be improved for utilization as biofertilizer, biopesticides, etc., instead of using harmful chemical biofertilizers. Moreover, plant growth-promoting microbe inoculants can enhance crop productivity. Although, scientists have discussed several tools and techniques by omics and gene editing approaches for crop improvement to avoid biotic and abiotic stress and make the plant healthier and more nutritive. However, beneficial soil microbes that help plants with the nutrient acquisition, development, and stress resistance were ignored, and farmers started utilizing chemical fertilizers. Thus, this review attempts to summarize the interaction system of plant microbes, the role of beneficiary soil microbes in the rhizosphere zone, and their role in plant health promotion, particularly in the nutrition acquisition of the plant. The review will also provide a better understanding of soil microbes that can be exploited as biofertilizers and plant growth promoters in the field to create environmentally friendly, sustainable agriculture systems.

SILIA-Based 4C Quantitative PTM Proteomics

To absolutely and relatively quantitate the alteration of a posttranslationally modified (PTM) proteome in response to a specific internal or external signal, a ¹⁵N-stable isotope labeling in Arabidopsis (SILIA) protocol has been integrated into the 4C quantitative PTM proteomics, named as SILIA-based 4C quantitative PTM proteomics (S4Quap). The isotope metabolic labeling produces both forward (F) and reciprocal (R) mixings of either ¹⁴N/¹⁵N-coded tissues or the ¹⁴N/¹⁵N-coded total cellular proteins. Plant protein is isolated using a urea-based extraction buffer (UEB). The presence of 8 M urea, 2% polyvinylpolypyrrolidone (PVPP), and 5 mM ascorbic acid allows to instantly denature protein, remove the phenolic compounds, and curb the oxidation by free radicals once plant cells are broken. The total cellular proteins are routinely processed into peptides by trypsin. The PTM peptide yield of affinity enrichment and preparation is 0.1-0.2% in general. Ion exchange chromatographic fractionation prepares the PTM peptides for LC-MS/MS analysis. The collected mass spectrograms are subjected to a target-decoy sequence analysis using various search engines. The computational programs are subsequently applied to analyze the ratios of the extracted ion chromatogram (XIC) of the ¹⁴N/¹⁵N isotope-coded PTM peptide ions and to perform the statistical evaluation of the quantitation results. The Student t-test values of ratios of quantifiable ¹⁴N/¹⁵N-coded PTM peptides are normally corrected using a Benjamini-Hochberg (BH) multiple hypothesis test to select the significantly regulated PTM peptide groups (BH-FDR < 5%). Consequently, the highly selected prospect candidate(s) of PTM proteins are confirmed and validated using biochemical, molecular, cellular, and transgenic plant analysis.

Dual activities of ACC synthase: Novel clues regarding the molecular evolution of ACS genes

Ethylene plays profound roles in plant development. The rate-limiting enzyme of ethylene biosynthesis is 1-aminocyclopropane-1-carboxylate (ACC) synthase (ACS), which is generally believed to be a single-activity enzyme evolving from aspartate aminotransferases. Here, we demonstrate that, in addition to catalyzing the conversion of S-adenosyl-methionine to the ethylene precursor ACC, genuine ACSs widely have C_β-S lyase activity. Two N-terminal motifs, including a glutamine residue, are essential for conferring ACS activity to ACS-like proteins. Motif and activity analyses of ACS-like proteins from plants at different evolutionary stages suggest that the ACC-dependent pathway is uniquely developed in seed plants. A putative catalytic mechanism for the dual activities of ACSs is proposed on the basis of the crystal structure and biochemical data. These findings not only expand our current understanding of ACS functions but also provide novel insights into the evolutionary origin of ACS genes.

Progress of ethylene action mechanism and its application on plant type formation in crops

The plant hormone ethylene exerts a huge influence in the whole life cycle of plants, especially stress-resistance responses. With the development of functional genomics, that the action mechanism of ethylene takes part in mediated plant architecture has been clarified gradually, such as plant roots, stems, leaves, fiber elongation and so on. Accordingly, the application of ethylene on crops chemical control and genetic improvement is greatly expanded. From the view of ethylene mediated plant architecture in crops, here reviewed advances in ethylene biosynthesis and signal transduction pathway, stress-resistance responses and the yield potential enhance of crops in recently 20 years. On these grounds, the objectives of this paper were to provide scientific reference and a useful clue for the crop creation of ideal plant type.

Quantitative and Functional Phosphoproteomic Analysis Reveals that Ethylene Regulates Water Transport via the C-Terminal Phosphorylation of Aquaporin PIP2;1 in Arabidopsis

Ethylene participates in the regulation of numerous cellular events and biological processes, including water loss, during leaf and flower petal wilting. The diverse ethylene responses may be regulated via dynamic interplays between protein phosphorylation/dephosphorylation and ubiquitin/26S proteasome-mediated protein degradation and protease cleavage. To address how ethylene alters protein phosphorylation through multi-furcated signaling pathways, we performed a (15)N stable isotope labelling-based, differential, and quantitative phosphoproteomics study on air- and ethylene-treated ethylene-insensitive Arabidopsis double loss-of-function mutant ein3-1/eil1-1. Among 535 non-redundant phosphopeptides identified, two and four phosphopeptides were up- and downregulated by ethylene, respectively. Ethylene-regulated phosphorylation of aquaporin PIP2;1 is positively correlated with the water flux rate and water loss in leaf. Genetic studies in combination with quantitative proteomics, immunoblot analysis, protoplast swelling/shrinking experiments, and leaf water loss assays on the transgenic plants expressing both the wild-type and S280A/S283A-mutated PIP2;1 in the both Col-0 and ein3eil1 genetic backgrounds suggest that ethylene increases water transport rate in Arabidopsis cells by enhancing S280/S283 phosphorylation at the C terminus of PIP2;1. Unknown kinase and/or phosphatase activities may participate in the initial up-regulation independent of the cellular functions of EIN3/EIL1. This finding contributes to our understanding of ethylene-regulated leaf wilting that is commonly observed during post-harvest storage of plant organs.

Expression and regulation of pear 1-aminocyclopropane-1-carboxylic acid synthase gene (PpACS1a) during fruit ripening, under salicylic acid and indole-3-acetic acid treatment, and in diseased fruit

In plants, the level of ethylene is determined by the activity of the key enzyme 1-aminocyclopropane-1-carboxylic acid (ACC) synthase (ACS). A gene encoding an ACC synthase protein was isolated from pear (Pyrus pyrifolia). This gene designated PpACS1a (GenBank accession no. KC632526) was 1488 bp in length with an open reading frame (ORF) encoding a protein of 495 amino acids that shared high similarity with other pear ACC synthase proteins. The PpACS1a was grouped into type-1 subfamily of plant ACS based on its conserved domain and phylogenetic status. Real-time quantitative PCR indicated that PpACS1a was differentially expressed in pear tissues and predominantly expressed in anthers. The expression signal of PpACS1a was also detected in fruit and leaves, but no signal was detected in shoots and petals. Furthermore, the PpACS1a expression was regulated during fruit ripening. In addition, the PpACS1a gene expression was regulated by salicylic acid (SA) and indole-3-acetic acid (IAA) in fruit. Moreover, the expression of the PpACS1a was up-regulated in diseased pear fruit. These results indicated that PpACS1a might be involved in fruit ripening and response to SA, IAA and disease.

The FAST technique: a simplified Agrobacterium-based transformation method for transient gene expression analysis in seedlings of Arabidopsis and other plant species

BACKGROUND

Plant genome sequencing has resulted in the identification of a large number of uncharacterized genes. To investigate these unknown gene functions, several transient transformation systems have been developed as quick and convenient alternatives to the lengthy transgenic assay. These transient assays include biolistic bombardment, protoplast transfection and Agrobacterium-mediated transient transformation, each having advantages and disadvantages depending on the research purposes.

RESULTS

We present a novel transient assay based on cocultivation of young Arabidopsis (Arabidopsis thaliana) seedlings with Agrobacterium tumefaciens in the presence of a surfactant which does not require any dedicated equipment and can be carried out within one week from sowing seeds to protein analysis. This Fast Agro-mediated Seedling Transformation (FAST) was used successfully to express a wide variety of constructs driven by different promoters in Arabidopsis seedling cotyledons (but not roots) in diverse genetic backgrounds. Localizations of three previously uncharacterized proteins were identified by cotransformation with fluorescent organelle markers. The FAST procedure requires minimal handling of seedlings and was also adaptable for use in 96-well plates. The high transformation efficiency of the FAST procedure enabled protein detection from eight transformed seedlings by immunoblotting. Protein-protein interaction, in this case HY5 homodimerization, was readily detected in FAST-treated seedlings with Förster resonance energy transfer and bimolecular fluorescence complementation techniques. Initial tests demonstrated that the FAST procedure can also be applied to other dicot and monocot species, including tobacco, tomato, rice and switchgrass.

CONCLUSION

The FAST system provides a rapid, efficient and economical assay of gene function in intact plants with minimal manual handling and without dedicated device. This method is potentially ideal for future automated high-throughput analysis.

Inter-dependence of dimerization and organelle binding in myosin XI

Cytoplasmic streaming is a ubiquitous process in plant cells that is thought to be driven by the active movement of myosin XI motor proteins along actin filaments. These myosin motors bind to organelles through their C-terminal globular tail domain, although recent studies have also suggested a role for the central coiled-coil region during organelle binding. Here we have investigated the relationship between these two protein domains of MYA1, an Arabidopsis myosin XI, in a series of in vivo experiments demonstrating that dimerization of the coiled-coil region stabilizes organelle binding of the globular tail. Surprisingly, yeast two-hybrid assays, bimolecular fluorescence complementation, Förster resonance energy transfer and in vitro pull-down experiments all demonstrated that dimerization of the 174-residue MYA1 coiled coils by themselves was unstable. Furthermore, only the first of the two major coiled-coil segments in MYA1 contributed significantly to dimer formation. Interestingly, dimerization of myosin tail constructs that included the organelle-binding globular tail was stable, although the globular tails by themselves did not interact. This suggests an inter-dependent relationship between dimerization and organelle binding in myosin XI, whereby each process synergistically stimulates the other.