All major cholesterol-dependent cytolysins use glycans as cellular receptors

Cholesterol-dependent cytolysins (CDCs) form pores in cholesterol-rich membranes, but cholesterol alone is insufficient to explain their cell and host tropism. Here, we show that all eight major CDCs have high-affinity lectin activity that identifies glycans as candidate cellular receptors. Streptolysin O, vaginolysin, and perfringolysin O bind multiple glycans, while pneumolysin, lectinolysin, and listeriolysin O recognize a single glycan class. Addition of exogenous carbohydrate receptors for each CDC inhibits toxin activity. We present a structure for suilysin domain 4 in complex with two distinct glycan receptors, P1 antigen and αGal/Galili. We report a wide range of binding affinities for cholesterol and for the cholesterol analog pregnenolone sulfate and show that CDCs bind glycans and cholesterol independently. Intermedilysin binds to the sialyl-TF O-glycan on its erythrocyte receptor, CD59. Removing sialyl-TF from CD59 reduces intermedilysin binding. Glycan-lectin interactions underpin the cellular tropism of CDCs and provide molecular targets to block their cytotoxic activity.Lucy K. Shewell, Christopher J. Day, Freda E.-C. Jen, Thomas Haselhorst, John M. Atack, Josephine F. Reijneveld, Arun Everest-Dass, David B. A. James, Kristina M. Boguslawski, Stephan Brouwer, Christine M. Gillen, Zhenyao Luo, Bostjan Kobe, Victor Nizet, Mark von Itzstein, Mark J. Walker, Adrienne W. Paton, James C. Paton, Victor J. Torres, Michael P. Jenning

Structure and function of nucleotide sugar transporters: Current progress

Contains fulltext : 136868.pdf (publisher's version ) (Open Access)The proteomes of eukaryotes, bacteria and archaea are highly diverse due, in part, to the complex post-translational modification of protein glycosylation. The diversity of glycosylation in eukaryotes is reliant on nucleotide sugar transporters to translocate specific nucleotide sugars that are synthesised in the cytosol and nucleus, into the endoplasmic reticulum and Golgi apparatus where glycosylation reactions occur. Thirty years of research utilising multidisciplinary approaches has contributed to our current understanding of NST function and structure. In this review, the structure and function, with reference to various disease states, of several NSTs including the UDP-galactose, UDP-N-acetylglucosamine, UDP-N-acetylgalactosamine, GDP-fucose, UDP-N-acetylglucosamine/UDP-glucose/GDP-mannose and CMP-sialic acid transporters will be described. Little is known regarding the exact structure of NSTs due to difficulties associated with crystallising membrane proteins. To date, no three-dimensional structure of any NST has been elucidated. What is known is based on computer predictions, mutagenesis experiments, epitope-tagging studies, in-vitro assays and phylogenetic analysis. In this regard the best-characterised NST to date is the CMP-sialic acid transporter (CST). Therefore in this review we will provide the current state-of-play with respect to the structure-function relationship of the (CST). In particular we have summarised work performed by a number groups detailing the affect of various mutations on CST transport activity, efficiency, and substrate specificity

Avian influenza H5-containing virus-like particles (VLPs): Host-cell receptor specificity by STD NMR spectroscopy

(Figure Presented) Gripped by the flu: The emergence of a human pandemic influenza virus from an avian progenitor involves a switch in preferential binding of the influenza virus hemagglutinin (HA). Saturation transfer difference NMR spectroscopy of avian H5 chimeric virus-like particles (VLPs) encoding viral HA in a complex with α(2,3)-and α(2,6)-linked N-acetylneuraminides (3′SL and 6′SL, respectively) has shown that avian influenza H5-containing VLPs clearly discriminate between α(2,3)-and α(2,6)-linkages. © 2008 Wiley-VCH Verlag GmbH & Co. KGaA.link_to_subscribed_fulltex

Investigation of the binding and cleavage characteristics of N1 neuraminidases from avian, seasonal, and pandemic influenza viruses using saturation transfer difference nuclear magnetic resonance

The main function of influenza neuraminidase (NA) involves enzymatic cleavage of sialic acid from the surface of host cells resulting in the release of the newly produced virions from infected cells, as well as aiding the movement of virions through sialylated mucus present in the respiratory tract. However, there has previously been little information on the binding affinity of different forms of sialylated glycan with NA. Our objectives were then to investigate both sialic acid binding and cleavage of neuraminidase at an atomic resolution level.link_to_OA_fulltex

Influenza C virus and bovine coronavirus esterase reveal a similar catalytic mechanism: new insights for drug discovery

Both, the influenza C (INF-C) virus haemagglutinin esterase fusion and bovine coronavirus (BCoV) haemagglutinin esterase surface glycoproteins exhibit a lectin binding capability and a receptor-destroying 9-O-acetyl esterase activity that recognise 9-O-acetyl-N-acetylneuraminic acid (Neu5,9Ac2)-containing glycans. Here we report nuclear magnetic resonance and molecular modelling studies on the 9-O-acetyl esterase showing that the α-configured Neu5,9Ac2 is strictly preferred by the INF-C and BCoV esterases. Interestingly, we have discovered that the INF-C esterase function releases acetate independently of the chemical nature of the aglycon moiety, whereas subtle differences in substrate recognition were found for BCoV esterase. Analysis of the apo and complexed X-ray crystal structure of INF-C esterase revealed that binding of 9-O-acetylated N-acetylneuraminic acids is a dynamic process that involves conformational rearrangement of serine-57 in the esterase active site. This study provides valuable insights towards the design of drugs to combat INF-C virus and coronavirus infections causing outbreaks of upper respiratory infections and severe diarrhea in calves, respectively

Influenza C virus and bovine coronavirus esterase reveal a similar catalytic mechanism: new insights for drug discovery

Both, the influenza C (INF-C) virus haemagglutinin esterase fusion and bovine coronavirus (BCoV) haemagglutinin esterase surface glycoproteins exhibit a lectin binding capability and a receptor-destroying 9-O-acetyl esterase activity that recognise 9-O-acetyl-N-acetylneuraminic acid (Neu5,9Ac2)-containing glycans. Here we report nuclear magnetic resonance and molecular modelling studies on the 9-O-acetyl esterase showing that the α-configured Neu5,9Ac2 is strictly preferred by the INF-C and BCoV esterases. Interestingly, we have discovered that the INF-C esterase function releases acetate independently of the chemical nature of the aglycon moiety, whereas subtle differences in substrate recognition were found for BCoV esterase. Analysis of the apo and complexed X-ray crystal structure of INF-C esterase revealed that binding of 9-O-acetylated N-acetylneuraminic acids is a dynamic process that involves conformational rearrangement of serine-57 in the esterase active site. This study provides valuable insights towards the design of drugs to combat INF-C virus and coronavirus infections causing outbreaks of upper respiratory infections and severe diarrhea in calves, respectively

A secondary sialic acid binding site on influenza virus neuraminidase: fact or fiction?

One flu over the cuckoo's nest: The biological significance of a secondary sialic acid binding site on influenza virus neuraminidase remains elusive. On blocking the active site influenza-virus-containing virus-like particles with oseltamivir carboxylate, binding to α(2,3)-sialyllactose is still detected. Thus the sialyllactose must bind at a secondary sialic acid binding site (see structures: docking study of α(2,3)-sialyllactose in the secondary binding site of avian flu neuraminidase). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.link_to_subscribed_fulltex