Glycosyltransferases definition of glycosyltransferases by. Nevertheless, enzymatic properties, folding, substrate specificities, and catalytic mechanisms of these enzyme proteins may have significant similarity. Understanding gts at the molecular level, through structural and kinetic studies. Glycosylation reactions mainly catalyzed by glycosyltransferases gts occur almost everywhere in the biosphere, and always play crucial roles in vital processes. Glycosyltransferases were initially considered to be specific for a single glycosyl donor and acceptor, which led to the one enzymeone linkage concept. Advances in understanding glycosyltransferases from a structural perspective tracey m gloster glycosyltransferases gts, the enzymes that catalyse glycosidic bond formation, create a diverse range of saccharides and glycoconjugates in nature. They found that the nterminal domain of vlde is responsible for its distinct substrate specificity and catalytic activity, and that the chimeric proteins can produce hybrid pseudoaminodisaccharides. Withers1 1department of chemistry, university of british columbia, vancouver v6t 1z3, canada. Yet, unlike dna or proteins, carbohydrates are made without a template to follow. Although several natural product glycosyltransferase structures have been reported, design principles of glycosyltransferase engineering for the generation of glycodiversified natural products has fallen short of its promise, partly due to a lack of understanding of the relationship. Determining both the sugar donor and acceptor for a gt of unknown function can be challenging, and is. However, in contrast to otsa, which catalyzes condensation between udpglucose and glucose 6phosphate, vlde couples two pseudosugars to give a product with an. Characterization of the glycosyltransferase gene ugt78h2. Glycosyltransferases can be classified as either retaining or inverting.
Structure, mechanism and engineering of plant natural product glycosyltransferases xiaoqiang wang plant biology division, samuel roberts noble foundation, 2510 sam noble parkway, ardmore, ok 73401, united states article info article history. In the three domains of life, lipidlinked glycans contribute to various cellular processes ranging from protein glycosylation to glycosylphosphatidylinositol anchor biosynthesis to peptidoglycan assembly. Golgi gtases are almost invariably type ii integral membrane proteins, with the cterminal globular catalytic domain residing in the. Deep evolutionary analysis reveals the design principles of.
Structures, functions, and mechanisms glycosyltransferases catalyze glycosidic bond formation using sugar donors containing a nucleoside phosphate or a lipid. Bacterial glycosyltransferases gt often synthesize the same glycan linkages as mammalian gt. Different mechanisms evolved by which eps are synthesized. To date, 95 families of glycosyltransferases have been defined, which encompass more than 30000 putative glycosyltransferases. Carbohydrates are one of the major groups of large biological molecules that regulate nearly all aspects of life. Golgi gtases are almost invariably type ii integral membrane proteins, with the cterminal globular catalytic domain residing in. Frontiers crossroads between bacterial and mammalian. Journal of the american chemical society 2015, 7 24, 75287547. In generating many of these glycoconjugates, phosphorylated polyprenolbased lipids are charged with single sugars by polyprenol phosphate glycosyltransferases. Feb 21, 2006 glycosyltransferases gts catalyze the transfer of a sugar moiety from an activated donor sugar onto saccharide and nonsaccharide acceptors. Structures of trehalose6phosphate phosphatase from.
Therefore, where the structure and mechanism of a gt member for a given family. In order to understand the full potential of gts, the chemical and structural glycosylation mechanisms are systematically summarized in this revie. Deep evolutionary analysis reveals the design principles. Mining of efficient microbial udpglycosyltransferases by. The product of glycosyl transfer may be an o, n, s, or cglycoside. Glycosyltransferases catalyze glycosidic bond formation using sugar donors containing a nucleoside phosphate or a lipid. Glycosyltransferases are useful synthetic catalysts for generating natural products with sugar moieties. These findings will provide scientists with new hypotheses for investigating the complex relationships connecting the genetic information about glycosyltransferases with their structures and activities. Crystal structures of eukaryote glycosyltransferases reveal.
Advances in understanding glycosyltransferases from a. A the inverting polyprenol phosphate gts that share a common gta fold are generally believed to adopt an s n 2, directdisplacement mechanism wherein the udp leaving group is coordinated via mgii to an aspxaaasp motif that is generally wellconserved among all the gta fold gts. Here, we report three glycosyltransferases from the leaves of a. At the left is a lectin from a seed pdb entry 1lu1, with four binding sites for carbohydrates in all of these pictures, the structure includes a few sugars from the longer natural carbohydrate chain, shown here in green. Therefore, where the structure and mechanism of a gt member for a given family has been. Jan, 2017 linking sugar molecules together to make complex carbohydrates is a geometrical challenge. Glycosyltransferases gtases transfer sugar moieties to proteins, lipids or existing glycan or polysaccharide molecules. However, only family 6 gts exhibit a putative nucleophile protein residue properly located in the active site to. Andrographis paniculata is an important traditional medicinal herb in south and southeast asian countries with diverse pharmacological activities that contains various flavonoids and flavonoid glycosides.
They catalyze the transfer of saccharide moieties from an activated nucleotide sugar also known as the glycosyl donor to a nucleophilic glycosyl acceptor molecule, the nucleophile of which can be oxygen carbon, nitrogen, or sulfurbased the result of glycosyl transfer can be a carbohydrate. Identification of quantitative trait loci for the fatty acid composition in korean native chicken native grapevine enzymes called glycosyltransferases bind sugar molecules to the volatile phenols, rendering them odorless and hidden within the juice. All proteins of a same cazy family have likely evolved from the same progenitor sequence, present conserved mechanisms of reaction, and. Glycosyltransferases are key enzymes in a range of biological processes. An evolutionary view of functional diversity in family 1. Nov 29, 2006 classification of glycosyltransferases according to sequence homology reveals at least 86 families. Crystal structures of eukaryote glycosyltransferases. However, only family 6 gts exhibit a putative nucleophile protein residue properly located in the active site to participate in. A chemical rescue methodology is here applied to a retaining. Significantly, the enzymes that synthesize trehalose are absent in humans, and thus serve as potential targets for novel antifungal intervention.
The functions of these ugts remain to be clarified. Disrupted glycosylation of lipids and proteins is a cause of. Distinct substrate specificity and catalytic activity of. Glycosyltransferases definition of glycosyltransferases. To survive in their human host, pathogenic fungi require the disaccharide, trehalose. All proteins of a same cazy family have likely evolved from the same progenitor sequence, present conserved mechanisms of reaction, and share similar structural folds. Fungal infections pose a serious threat to human health and result in several million deaths annually. Insights from ab initio quantum mechanicsmolecular mechanics dynamic simulations. A third fold was predicted, but only in 2008 the first three dimensional structure was established of a gtc enzyme. Arginineglcnacylation of death domain and nlebssek. To date, the 3d structures of glycosyltransferases have been roughly grouped into three folds, designated as gta, gtb, and gtc 23,24. Gtases form an important group of enzymes in the golgi, where the synthesis and modification of glycoproteins and glycolipids take place. Azide as exogenous nucleophile rescues the activity of the inactive e317a mutant to give. Structures, functions, and mechanisms only two structural folds, gta and gtb, have been identified for the nucleotide sugardependent enzymes, but other folds are now appearing for the soluble domains of lipid phosphosugardependent glycosyl transferases.
Received 17 august 2009 revised 24 september 2009 accepted 25 september 2009 available online 29. Only two structural folds, gta and gtb, have been identified for the nucleotide sugardependent enzymes, but other folds are now appearing for the soluble domains of lipid phosphosugardependent glycosyl transferases. By analogy to the wellestablished mechanism of retaining glycosidases, it was first suggested that retgts follow a doubledisplacement mechanism. New structures, chemical functions, and inhibitors for. Mechanistic evidence for a frontside, s n itype reaction in. Although the 3d structures of all enzymes have not been solved to date, recent progress in structural analysis of these glycosyltransferases has provided insights into substrate recognition and catalytic reaction mechanisms. N2 glycosyltransferases catalyze glycosidic bond formation using sugar donors containing a nucleoside phosphate or a lipid phosphate leaving group.
Recent structures, evolution and mechanisms of glycosyltransferases. Crossroads between bacterial and mammalian glycosyltransferases. Structural analyses also clarify the selective reaction mechanisms of glycosyltransferases for target glycoproteins, leading to the rational design of glycanbased inhibitors. The last two years have seen a new appreciation for the range of structural folds that can be adopted by this class of enzymes in addition to continued work in solving the structures of more varieties of these proteins, delineating their chemical function, and designing inhibitors of their catalytic function.
However, the exact mechanisms of sugar donor or acceptor substrate recognition are still to be elusive. Distinct substrate specificity and catalytic activity of the. Both double displacement and front side single displacement sni mechanisms have been proposed. Hybrid quantum mechanicalmolecular mechanical study of inverting nacetylglucosaminyltransferase i. However, cytokinin glycosyltransferases from phaseolus spp. For a sixcarbon sugar such as glucose, there are six different possible linkage sites and also two possible configurations in which to anchor the incipient bond. Structure, mechanism and engineering of plant natural product. The catalytic mechanism of gnti was investigated using a hybrid quantum mechanicalmolecular mechanical qmmm method with a qm. Nov 25, 2017 figure 2 catalytic mechanisms of inverting and retaining polyprenol phosphate glycosytransferases gts. Linking sugar molecules together to make complex carbohydrates is a geometrical challenge. We reported the isolation of a new glycosyltransferase gene from blackberry plants rubus spp. The known structures of glycosyltransferases have allowed the establishment of two basic categories of enzymes. Glycosyltransferases are ubiquitous proteins involved in such reactions. Structural basis for the glycosyltransferase activity of the salmonella.
Glycosylation is one of the mechanisms maintaining cellular homeostasis through the regulation of the level, biological activity, and subcellular distribution of the glycosylated compounds. Thus, bacterial gt can be utilized for the enzymatic synthesis of both bacterial and mammalian. The mechanism of retaining glycosyltransferases is still poorly understood and the subject of current debate. Abuelizz and mahmud used otsa, vlde, and chimeric proteins to study pseudoglycosyltransferase catalysis. Advances in understanding glycosyltransferases from a structural. Sugar mono or diphosphonucleotides, in which case the resulting enzymes are referred to as leloir glycosyltransferases. Sep 20, 2017 glycosyltransferases gtases transfer sugar moieties to proteins, lipids or existing glycan or polysaccharide molecules. A sequencebased classification spreads gts in many families thus reflecting the variety of molecules that can be used as acceptors. The golgi glycosyltransferase, nacetylglucosaminyltransferase i gnti, catalyzes the transfer of a glcnac residue from the donor udpglcnac to the c2hydroxyl group of a mannose residue in the trimannosyl core of the man5glcnac2. Subsequent observations have refuted the theory of absolute enzymatic specificity by describing the transfer of analogs of some nucleoside mono or diphosphate sugar donors. Classification and recent structures of glycosyltransferases.
Nonnucleotide carbohydrate donors including various sugar polyprenol mono or diphosphates, in which case the enzymes are referred to as non. Structures, functions, and mechanisms glycosyltransferases catalyze glycosidic bond formation using sugar donors. Structurefunction relationships of membraneassociated gt. Complete set of glycosyltransferase structures in the. Fiftyone human glycosyltransferases were expressed in saccharomyces cerevisiae as immobilized enzymes and were assayed for enzymatic activities.
Structure, mechanism and engineering of plant natural. Construction of a library of human glycosyltransferases. In contrast, this enzyme family is characterized by a more conserved threedimensional architecture. The stem and catalytic regions of sialyl, fucosyl, galactosyl, n acetylgalactosaminyl, and n acetylglucosaminyltransferases were fused with yeast cell wall pir proteins, which anchor glycosyltransferases at the yeast cell wall glucan. The glycosides play various functions in plant cells, such as highenergy donors, or signalling molecules, and are involved in biosynthesis of cell walls. Glycosyltransferases gts catalyze the transfer of a sugar moiety from an activated donor sugar onto saccharide and nonsaccharide acceptors. The pseudoglycosyltransferase psgt vlde is a glycosyltransferaselike protein that is similar to trehalose 6phosphate synthase otsa. The catalytic mechanism of retaining glycosyltransferases retgts remains a controversial issue in glycobiology. Here, we describe multiple structures of one of the trehalose. One of their important roles is in the biosynthesis of disaccharides, oligosaccharides, and polysaccharides by catalyzing the transfer of sugar moieties from activated donor molecules to other sugar molecules. Glycosyltransferases gtfs, gtfs are enzymes that establish natural glycosidic linkages. The blood type carbohydrates provide ready handles for attachment, and are exploited by many organisms.
Mar 28, 2017 the sequence identities of target proteins are in the socalled twilight zone, thus it is difficult to accurately predict the target protein structures and functions through bioinformatics methods. Glycosyltransferase structure and function springerlink. Pdf structures and mechanism of glycosyltransferases. These enzymes utilize activated sugar phosphates as glycosyl donors, and catalyze glycosyl group transfer to a nucleophilic group, usually an alcohol. Glycosyltransferases catalyze glycosidic bond formation using sugar donors containing a nucleoside phosphate or a lipid phosphate leaving group. In addition gts also catalyze the transfer of sugar. A mechanism involving a shortlived oxocarbenium ion. This is in sharp contrast with glycosylhydrolases, which to date have published structures for 70 of the so far described 102 classes. Apr 01, 2020 this framework could make predictions with nearly 90% accuracy based only on information that can be deciphered from the gene for that enzyme.
Structures and mechanisms of glycosyltransferases glycobiology. A number of studies have implicated glycosyltransferases in the pathogenesis of neurodegenerative diseases but differentiating cause from effect has been difficult. Glycosyltransferases are enzymes that catalyze the formation of the glycosidic linkage to form a glycoside. The sequence identities of target proteins are in the socalled twilight zone, thus it is difficult to accurately predict the target protein structures and functions through bioinformatics methods. Classification of glycosyltransferases according to sequence homology reveals at least 86 families. Nlinked glycosylation plays a role in various cellular functions including protein folding, quality. Instead, these molecules are built from a set of sugarbased building blocks by the intricate activities of a large and diverse family of enzymes known as glycosyltransferases. They catalyze the transfer of saccharide moieties from an activated nucleotide sugar also known as the glycosyl donor to a nucleophilic glycosyl acceptor molecule, the nucleophile of which can be oxygen carbon, nitrogen, or sulfur based. This first structure of a retaining gta arginine nglycosyltransferase. Glycosyltransferases utilize various sugar1phosphate derivatives including. Disrupted glycosylation of lipids and proteins is a cause. Mechanistic evidence for a frontside, s n itype reaction.
Arginineglcnacylation of death domain and nleb ssek. Oct 25, 2011 glycosyltransferases are useful synthetic catalysts for generating natural products with sugar moieties. Identification of quantitative trait loci for the fatty acid composition in korean native chicken native grapevine enzymes called glycosyltransferases bind sugar molecules to the volatile phenols, rendering them odorless and. Insights into the structure and function of membrane. These molecules of enormous diversity mediate a wide range of functions from structure and storage to signalling. The prediction of the function of a putative gt of sequence homology.
Special focus will also be made on proteoglycan gt enzymes and unanswered questions about this major glycosylation pathway. Nov 14, 2019 glycosyltransferases represent a large family of enzymes that catalyse the biosynthesis of oligosaccharides, polysaccharides, and glycoconjugates. Despite their unique catalytic activity and important role in the. Glycosyltransferases represent a large family of enzymes that catalyse the biosynthesis of oligosaccharides, polysaccharides, and glycoconjugates. The biosynthesis of disaccharides, oligosaccharides and polysaccharides involves the action of hundreds of different glycosyltransferases gts ec 2. Insights into the synthesis of lipopolysaccharide and antibiotics through the structures of two retaining glycosyltransferases from family gt4. Although several natural product glycosyltransferase structures have been reported, design principles of glycosyltransferase engineering for the generation of glycodiversified natural products has fallen short of its promise, partly due to a lack of understanding of the relationship between.
306 908 1230 47 136 1173 837 272 1401 164 1379 473 843 478 1067 519 1154 1048 95 1002 515 1368 698 1039 1437 981 64 1049 886 140 751 185 1232 690 1016 947