Multiplex Fluorescent, Activity-Based Protein Profiling Identifies Active a-Glycosidases and Other Hydrolases in Plants 1[OPEN (original) (raw)
Related papers
Plant physiology, 2018
With nearly 140 α-glycosidases in 14 different families, plants are well equipped with enzymes that can break the α-glucosidic bonds in a large diversity of molecules. Here, we introduce activity-based protein profiling (ABPP) of α-glycosidases in plants using α-configured cyclophellitol aziridine probes carrying various fluorophores or biotin. In Arabidopsis (), these probes label members of the GH31 family of glycosyl hydrolases, including endoplasmic reticulum-resident α-glucosidase-II Radial Swelling3/Priority for Sweet Life5 (RSW3/PSL5) and Golgi-resident α-mannosidase-II Hybrid Glycosylation1 (HGL1), both of which trim -glycans on glycoproteins. We detected the active state of extracellular α-glycosidases such as α-xylosidase XYL1, which acts on xyloglucans in the cell wall to promote cell expansion, and α-glucosidase AGLU1, which acts in starch hydrolysis and can suppress fungal invasion. Labeling of α-glycosidases generates pH-dependent signals that can be suppressed by α-gl...
A Real-Time Fluorogenic Assay for the Visualization of Glycoside Hydrolase Activity in Planta
PLANT PHYSIOLOGY, 2009
There currently exists a diverse array of molecular probes for the in situ localization of polysaccharides, nucleic acids, and proteins in plant cells, including reporter enzyme strategies (e.g. protein-glucuronidase fusions). In contrast, however, there is a paucity of methods for the direct analysis of endogenous glycoside hydrolases and transglycosidases responsible for cell wall remodeling. To exemplify the potential of fluorogenic resorufin glycosides to address this issue, a resorufin b-glycoside of a xylogluco-oligosaccharide (XXXG-b-Res) was synthesized as a specific substrate for in planta analysis of XEH activity. The resorufin aglycone is particularly distinguished for high sensitivity in muro assays due to a low pK a (5.8) and large extinction coefficient (« 62,000 M 21 cm 21 ), long-wavelength fluorescence (excitation 571 nm/emission 585 nm), and high quantum yield (0.74) of the corresponding anion. In vitro analyses demonstrated that XXXG-b-Res is hydrolyzed by the archetypal plant XEH, nasturtium (Tropaeolum majus) NXG1, with classical Michaelis-Menten substrate saturation kinetics and a linear dependence on both enzyme concentration and incubation time. Further, XEH activity could be visualized in real time by observing the localized increase in fluorescence in germinating nasturtium seeds and Arabidopsis (Arabidopsis thaliana) inflorescent stems by confocal microscopy. Importantly, this new in situ XEH assay provides an essential complement to the in situ xyloglucan endotransglycosylase assay, thus allowing delineation of the disparate activities encoded by xyloglucan endotransglycosylase/ hydrolase genes directly in plant tissues. The observation that XXXG-b-Res is also hydrolyzed by diverse microbial XEHs indicates that this substrate, and resorufin glycosides in general, may find broad applicability for the analysis of wall restructuring by polysaccharide hydrolases during morphogenesis and plant-microbe interactions.
Broad-range Glycosidase Activity Profiling
Plants produce hundreds of glycosidases. Despite their importance in cell wall (re)modeling, protein and lipid modification, and metabolite conversion, very little is known of this large class of glycolytic enzymes, partly because of their post-translational regulation and their elusive substrates. Here, we applied activity-based glycosidase profiling using cell-permeable small molecular probes that react covalently with the active site nucleophile of retaining glycosidases in an activity-dependent manner. Using mass spectrometry we detected the active state of dozens of myrosinases, glucosidases, xylosidases, and galactosidases representing seven different retaining glycosidase families. The method is simple and applicable for different organs and different plant species, in living cells and in subproteomes. We display the active state of previously uncharacterized glycosidases, one of which was encoded by a previously declared pseudogene. Interestingly, glycosidase activity profiling also revealed the active state of a diverse range of putative xylosidases, galactosidases, glucanases, and heparanase in the cell wall of Nicotiana benthamiana. Our data illustrate that this powerful approach displays a new and important layer of functional proteomic information on the active state of glycosidases.
Plants, 2014
Techniques for in situ localization of gene products provide indispensable information for understanding biological function. In the case of enzymes, biological function is directly related to activity, and therefore, knowledge of activity patterns is central to understanding the molecular controls of plant development. We have previously developed a novel type of fluorogenic substrate for revealing glycoside hydrolase activity in planta, based on resorufin β-glycosides Here, we explore a wider range of such substrates to visualize glycoside hydrolase activities in Arabidopsis inflorescence stems in real time, especially highlighting distinct distribution patterns of these activities in the secondary cell walls of
Plant Proteomics and Glycosylation
Plant Proteomics, 2006
In plant cells, as in other eucaryotic cells, glycosylation is one of the most studied posttranslational events. It can be of two types, N-or O-glycosylation, depending on the linkage involved between the protein backbone and the oligosaccharide moiety. In this review, we present different methods, commonly used in our laboratory, to study the glycosylation of plant proteins. These approaches rely on blot detection with glycanspecific probes, as well as specific deglycosylation of the glycoproteins, followed by mass spectrometry analysis. Such experiments not only allow determination of whether the protein is a glycoprotein, but also how and where it is glycosylated. The last part of this chapter is dedicated to the specific purification and identification of glycoprotein populations in plant cells, so-called glycoproteomics.
Plant Glycosides and Glycosidases: A Treasure-Trove for Therapeutics
Frontiers in Plant Science, 2020
Plants contain numerous glycoconjugates that are metabolized by specific glucosyltransferases and hydrolyzed by specific glycosidases, some also catalyzing synthetic transglycosylation reactions. The documented value of plant-derived glycoconjugates to beneficially modulate metabolism is first addressed. Next, focus is given to glycosidases, the central theme of the review. The therapeutic value of plant glycosidases is discussed as well as the present production in plant platforms of therapeutic human glycosidases used in enzyme replacement therapies. The increasing knowledge on glycosidases, including structure and catalytic mechanism, is described. The novel insights have allowed the design of functionalized highly specific suicide inhibitors of glycosidases. These so-called activity-based probes allow unprecedented visualization of glycosidases cross-species. Here, special attention is paid on the use of such probes in plant science that promote the discovery of novel enzymes and the identification of potential therapeutic inhibitors and chaperones.
Journal of Applied Glycoscience, 2012
Glycoside hydrolase family 1 (GH1) includes enzymes with a wide range of specificities in terms of reactions, substrates and products, with plant GH1 enzymes covering a particularly wide range of hydrolases and transglycosylases. In plants, in addition to β-D-glucosidases, β-D-mannosidases, disaccharidases, thioglucosidases and hydroxyisourate hydrolase, GH1 has recently been found to include galactosyl and glucosyl transferases that utilize galactolipid and acyl glucose donors, respectively. The amino acids binding to the ...
Functional genomic analysis of Arabidopsis thaliana glycoside hydrolase family 1
Plant Molecular Biology, 2004
In plants, Glycoside Hydrolase (GH) Family 1 β-glycosidases are believed to play important roles in many diverse processes including chemical defense against herbivory, lignification, hydrolysis of cell wall-derived oligosaccharides during germination, and control of active phytohormone levels. Completion of the Arabidopsis thalianagenome sequencing project has enabled us, for the first time, to determine the total number of Family 1 members in a higher plant. Reiterative database searches revealed a multigene family of 48 members that includes eight probable pseudogenes. Manual reannotation and analysis of the entire family were undertaken to rectify existing misannotations and identify phylogenetic relationships among family members. Forty-seven members (designated BGLU1 through BGLU47) share a common evolutionary origin and were subdivided into approximately 10 subfamilies based on phylogenetic analysis and consideration of intron–exon organizations. The forty-eighth member of this family (At3g06510; sfr2) is a β-glucosidase-like gene that belongs to a distinct lineage. Information pertaining to expression patterns and potential functions of Arabidopsis GH Family 1 members is presented. To determine the biological function of all family members, we intend to investigate the substrate specificity of each mature hydrolase after its heterologous expression in the Pichia pastoris expression system. To test the validity of this approach, the BGLU44-encoded hydrolase was expressed in P. pastoris and purified to homogeneity. When tested against a wide range of natural and synthetic substrates, this enzyme showed a preference for β-mannosides including 1,4-β-D-mannooligosaccharides, suggesting that it may be involved in A. thaliana in degradation of mannans, galactomannans, or glucogalactomannans. Supporting this notion, BGLU44 shared high sequence identity and similar gene organization with tomato endosperm β-mannosidase and barley seed β-glucosidase/β-mannosidase BGQ60.
The Plant Journal, 2003
Raf®nose and stachyose are ubiquitous galactosyl-sucrose oligosaccharides in the plant kingdom which play major roles, second only to sucrose, in photoassimilate translocation and seed carbohydrate storage. These sugars are initially metabolised by a-galactosidases (a-gal). We report the cloning and functional expression of the ®rst genes, CmAGA1 and CmAGA2, encoding for plant a-gals with alkaline pH optima from melon fruit (Cucumis melo L.), a raf®nose and stachyose translocating species. The alkaline a-gal genes show very high sequence homology with a family of unde®ned`seed imbibition proteins' (SIPs) which are present in a wide range of plant families. In order to con®rm the function of SIP proteins, a representative SIP gene, from tomato, was expressed and shown to have alkaline a-gal activity. Phylogenetic analysis based on amino acid sequences shows that the family of alkaline a-gals shares little homology with the known prokaryotic and eukaryotic a-gals of glycosyl hydrolase families 27 and 36, with the exception of two cross-family conserved sequences containing aspartates which probably function in the catalytic step. This previously uncharacterised, plant-speci®c a-gal family of glycosyl hydrolases, with optimal activity at neutral-alkaline pH likely functions in key processes of galactosyl-oligosaccharide metabolism, such as during seed germination and translocation of RFO photosynthate.