Mark R. Wormald

Bio: Mark R. Wormald is an academic researcher from University of Oxford. The author has contributed to research in topics: Glycosylation & Glycan. The author has an hindex of 64, co-authored 179 publications receiving 14686 citations. Previous affiliations of Mark R. Wormald include Hokuriku University & Katholieke Universiteit Leuven.

The Impact of Glycosylation on the Biological Function and Structure of Human Immunoglobulins

Abstract: Immunoglobulins are the major secretory products of the adaptive immune system. Each is characterized by a distinctive set of glycoforms that reflects the wide variation in the number, type, and location of their oligosaccharides. In a given physiological state, glycoform populations are reproducible; therefore, disease-associated alterations provide diagnostic biomarkers (e.g., for rheumatoid arthritis) and contribute to disease pathogenesis. The oligosaccharides provide important recognition epitopes that engage with lectins, endowing the immunoglobulins with an expanded functional repertoire. The sugars play specific structural roles, maintaining and modulating effector functions that are physiologically relevant and can be manipulated to optimize the properties of therapeutic antibodies. New molecular models of all the immunoglobulins are included to provide a basis for informed and critical discussion. The models were constructed by combining glycan sequencing data with oligosaccharide linkage and dynamics information from the Glycobiology Institute experimental database and protein structural data from "The Protein Data Bank."

Antibody Domain Exchange Is an Immunological Solution to Carbohydrate Cluster Recognition

Abstract: Human antibody 2G12 neutralizes a broad range of human immunodeficiency virus type 1 (HIV-1) isolates by binding an unusually dense cluster of carbohydrate moieties on the “silent” face of the gp120 envelope glycoprotein. Crystal structures of Fab 2G12 and its complexes with the disaccharide Manα1-2Man and with the oligosaccharide Man9GlcNAc2 revealed that two Fabs assemble into an interlocked VH domain-swapped dimer. Further biochemical, biophysical, and mutagenesis data strongly support a Fab-dimerized antibody as the prevalent form that recognizes gp120. The extraordinary configuration of this antibody provides an extended surface, with newly described binding sites, for multivalent interaction with a conserved cluster of oligomannose type sugars on the surface of gp120. The unique interdigitation of Fab domains within an antibody uncovers a previously unappreciated mechanism for high-affinity recognition of carbohydrate or other repeating epitopes on cell or microbial surfaces.

Glycosylation changes of IgG associated with rheumatoid arthritis can activate complement via the mannose-binding protein.

Abstract: The glycosylation of the circulating immunoglobulin-gamma (IgG) antibody molecules changes in rheumatoid arthritis The extent of the changes correlates with the disease severity and reverses in remission We demonstrate here that the alteration in glycosylation associated with rheumatoid arthritis can create a new mode for the interaction of IgG with complement through binding to the collagenous lectin mannose-binding protein (MBP) Rheumatoid arthritis is associated with a marked increases in IgG glycoforms that lack galactose (referred to as G0 glycoforms) in the Fc region of the molecule and that terminate in N-acetyl glucosamine (GlcNAc) We show, using nuclear magnetic resonance (NMR) and X-ray data, that these terminal GlcNAc residues become accessible for MBP binding We further demonstrate that multiple presentation of IgG-G0 glycoforms to MBP results in activation of the complement This suggests that a contribution to the chronic inflammation of the synovial membrane could arise from the localization of the IgG-G0 glycoforms in the affected joint and from resulting activation of complement

The Broadly Neutralizing Anti-Human Immunodeficiency Virus Type 1 Antibody 2G12 Recognizes a Cluster of α1→2 Mannose Residues on the Outer Face of gp120

Abstract: The humoral immune response to infection by human immunodeficiency virus type 1 (HIV-1) is typically characterized by relatively low levels of neutralizing antibodies, particularly those with broad activity against many different isolates of the virus (6, 23, 35, 36, 46). As might perhaps be anticipated from this observation, the induction of such antibodies by vaccination has proven largely elusive (9). At the same time, interest in inducing broadly neutralizing antibodies has increased as it becomes clear that antibodies can provide considerable benefit against HIV or simian immunodeficiency virus (SIV) challenge in animal models (1, 17, 30-32, 44, 55). Fortunately, natural infection is not completely barren of lessons for vaccine design since, although HIV elicits weak cross-neutralizing responses, a small number of human monoclonal antibodies (MAbs) with broad activities have been isolated from infected individuals (7, 8, 12, 59, 60). One rational contribution to eliciting neutralizing antibodies by vaccination is then to explore the interaction of these antibodies with virus envelope at the molecular level and incorporate the information obtained into immunogen design. Here, we seek to understand the interaction of one broadly neutralizing antibody with HIV-1 envelope. For some time, only three broadly neutralizing MAbs to HIV-1 were known (5, 12). Two of these MAbs bind to the surface glycoprotein, gp120, which is the viral receptor for CD4 and chemokine receptors CCR5 and CXCR4. These MAbs are b12, which recognizes an epitope overlapping the CD4 receptor site (7, 51), and 2G12, which recognizes an epitope based around the C4/V4 region of gp120 and is highly sensitive to the presence of N-linked glycans in this region (24, 60). One MAb, 2F5, binds to an epitope involving a linear motif (ELDKWA) on the membrane proximal region of the transmembrane envelope protein gp41 (8, 24, 43, 71). Recently, two MAbs, Z13 and 4E10, have been described which recognize a region close to the C terminus of the 2F5 epitope (56, 71). Another Fab with broad neutralizing ability, X5, recognizes a region close to the coreceptor binding site on gp120 and overlapping the epitope recognized by CD4-induced MAbs, such as 17b (37a). We focus here on the MAb 2G12. In vitro, this MAb has been shown to neutralize a wide spectrum of different HIV-1 isolates (59, 60), including those from different clades, with the notable exception of clade E. In vivo, the MAb protects macaques against vaginal challenge with the chimeric virus SHIV 89.6P (32). The antibody recognizes a unique epitope in that it does not compete with any of the large panel of MAbs to gp120 that have been produced (37). The binding of 2G12 to gp120 is inhibited by a number of mutations that disrupt sequences encoding attachment of N-linked carbohydrate chains (60). These sequences are located in the C2 and C3 regions around the base of the V3 loop, the C4 region, and the V4 loop. The crystal structure of the core of gp120 suggests that the carbohydrate attachment sites are clustered together on a part of the gp120 molecule known as the “silent face” (27, 28, 66, 67). This extensive solvent-accessible face is largely covered by carbohydrate and expected to be relatively weakly immunogenic and, hence, is described as immunologically silent. Carbohydrate-rich regions of glycoproteins are generally poorly immunogenic for a number of reasons. First, carbohydrates exhibit microheterogeneity; therefore, a single protein sequence would be expected to display multiple glycoforms, leading to the dilution of any single antigenic response (52). Second, large, potentially dynamic glycans (62, 64) can cover potential protein epitopes. Third, in the case of viruses, which depend on the host glycosylation machinery since they have none of their own, the oligosaccharides attached to potential antigens are the same as those attached to host glycoproteins. Therefore, in general, the host will display tolerance towards these sugars. The difficulty in eliciting antibodies to a carbohydrate face is consistent with the apparently unique nature of MAb 2G12. Despite the probable placement of the 2G12 epitope on the silent face (or at the junction of silent and neutralizing faces) (26, 27, 49, 60), we understand relatively little about the molecular nature of the epitope. We do not know whether the epitope is exclusively carbohydrate, exclusively protein with a requirement for carbohydrate to maintain local protein structure, or some combination of these. We do not know the relative importance of the different carbohydrate chains that are potentially involved or which sugar residues are likely to be crucial. To address these issues we have carried out a number of studies on the 2G12-gp120 interaction. These include a detailed glycan analysis of the gp120 N-linked carbohydrates, an examination of the effects of digestion of gp120 by various glycosidases, an analysis of the ability of various glycans and lectins to inhibit the interaction, extensive alanine scanning mutagenesis of gp120, sequence comparisons of gp120s with different abilities to interact with 2G12 and, finally, modeling studies of gp120. We conclude that Manα1→2Man-linked residues of the outer face of gp120 are required for the 2G12 epitope. Extensive site-directed mutagenesis demonstrated little dependence of 2G12 affinity on specific gp120 amino acid side chains.

Antibodies inhibit prion propagation and clear cell cultures of prion infectivity

Abstract: Prions are the transmissible pathogenic agents responsible for diseases such as scrapie and bovine spongiform encephalopathy. In the favoured model of prion replication, direct interaction between the pathogenic prion protein (PrPSc) template and endogenous cellular prion protein (PrPC) is proposed to drive the formation of nascent infectious prions. Reagents specifically binding either prion-protein conformer may interrupt prion production by inhibiting this interaction. We examined the ability of several recombinant antibody antigen-binding fragments (Fabs) to inhibit prion propagation in cultured mouse neuroblastoma cells (ScN2a) infected with PrPSc. Here we show that antibodies binding cell-surface PrPC inhibit PrPSc formation in a dose-dependent manner. In cells treated with the most potent antibody, Fab D18, prion replication is abolished and pre-existing PrPSc is rapidly cleared, suggesting that this antibody may cure established infection. The potent activity of Fab D18 is associated with its ability to better recognize the total population of PrPC molecules on the cell surface, and with the location of its epitope on PrPC. Our observations support the use of antibodies in the prevention and treatment of prion diseases and identify a region of PrPC for drug targeting.

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

The carbohydrate-active enzymes database (CAZy) in 2013

Abstract: The Carbohydrate-Active Enzymes database (CAZy; http://www.cazy.org) provides online and continuously updated access to a sequence-based family classification linking the sequence to the specificity and 3D structure of the enzymes that assemble, modify and breakdown oligo- and polysaccharides. Functional and 3D structural information is added and curated on a regular basis based on the available literature. In addition to the use of the database by enzymologists seeking curated information on CAZymes, the dissemination of a stable nomenclature for these enzymes is probably a major contribution of CAZy. The past few years have seen the expansion of the CAZy classification scheme to new families, the development of subfamilies in several families and the power of CAZy for the analysis of genomes and metagenomes. This article outlines the changes that have occurred in CAZy during the past 5 years and presents our novel effort to display the resolution and the carbohydrate ligands in crystallographic complexes of CAZymes.

Antibody neutralization and escape by HIV-1

Abstract: Neutralizing antibodies (Nab) are a principal component of an effective human immune response to many pathogens, yet their role in HIV-1 infection is unclear. To gain a better understanding of this role, we examined plasma from patients with acute HIV infection. Here we report the detection of autologous Nab as early as 52 days after detection of HIV-specific antibodies. The viral inhibitory activity of Nab resulted in complete replacement of neutralization-sensitive virus by successive populations of resistant virus. Escape virus contained mutations in the env gene that were unexpectedly sparse, did not map generally to known neutralization epitopes, and involved primarily changes in N-linked glycosylation. This pattern of escape, and the exceptional density of HIV-1 envelope glycosylation generally, led us to postulate an evolving 'glycan shield' mechanism of neutralization escape whereby selected changes in glycan packing prevent Nab binding but not receptor binding. Direct support for this model was obtained by mutational substitution showing that Nab-selected alterations in glycosylation conferred escape from both autologous antibody and epitope-specific monoclonal antibodies. The evolving glycan shield thus represents a new mechanism contributing to HIV-1 persistence in the face of an evolving antibody repertoire.