The Catalytic Mechanism of Human Parainfluenza Virus Type 3 Haemagglutinin-Neuraminidase Revealed

• Published in: Angewandte Chemie International Edition 2015-03, Vol.54 (10), p.2936-2940
• Main Authors: Dirr, Larissa, El-Deeb, Ibrahim M., Guillon, Patrice, Carroux, Cindy J., Chavas, Leonard M. G., von Itzstein, Mark
• Format: Article
• Language: English
• Subjects: Catalysis; Crystallography, X-Ray; haemagglutinin-neuraminidase; Hemagglutinin Glycoproteins, Influenza Virus - chemistry; Hemagglutinin Glycoproteins, Influenza Virus - metabolism; inhibitors; Magnetic Resonance Spectroscopy; Neuraminidase - chemistry; Neuraminidase - metabolism; parainfluenza virus; Parainfluenza Virus 3, Human - enzymology; Proton Magnetic Resonance Spectroscopy; sialic acid; sialidase mechanism
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201412243

Human parainfluenza virus type 3 (hPIV‐3) is one of the leading causes for lower respiratory tract disease in children, with neither an approved antiviral drug nor vaccine available to date. Understanding the catalytic mechanism of human parainfluenza virus haemagglutinin‐neuraminidase (HN) protein is key to the design of specific inhibitors against this virus. Herein, we used 1H NMR spectroscopy, X‐ray crystallography, and virological assays to study the catalytic mechanism of the HN enzyme activity and have identified the conserved Tyr530 as a key amino acid involved in catalysis. A novel 2,3‐difluorosialic acid derivative showed prolonged enzyme inhibition and was found to react and form a covalent bond with Tyr530. Furthermore, the novel derivative exhibited enhanced potency in virus blockade assays relative to its Neu2en analogue. These outcomes open the door for a new generation of potent inhibitors against hPIV‐3 HN. Antivirus update: 2,3‐difluoro sialic acid derivatives were used to explore the catalytic mechanism of human parainfluenza type 3 haemagglutinin‐neuraminidase. The enzyme is a retaining glycohydrolase and acts by a mechanism involving a covalent adduct formed between the key amino acid residue Tyr530 and the substrate. One sialic acid derivative showed potency in virus blockade assays and is thus a promising new lead in anti‐parainfluenza virus inhibitor design.