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NCBI PubMed ID: 4792393
Publication DOI: 10.7164/antibiotics.26.784
Journal NLM ID: 0151115
Publisher: London: Nature Publishing Group
Institutions: Research Laboratories of Meiji Seika Kaisha, Ltd. Morooka-cho, Kohoku-ku, Yokohama, Japan, Pharmaceutical Product Development Laboratoriesof Meiji Seika Kaisha, Ltd. Horikawa-cho, Saiwai-ku, Kawasaki, Japan
Methods: MS

Aspergillus fumigatus is a filamentous fungus that can cause severe respiratory disease in immunocompromised individuals. A putative sialidase from A. fumigatus was recently cloned and shown to be relatively poor in cleaving N-acetylneuraminic acid (Neu5Ac) in comparison with bacterial sialidases. Here we present the first crystal structure of a fungal sialidase. When the apo structure was compared with bacterial sialidase structures, the active site of the Aspergillus enzyme suggested that Neu5Ac would be a poor substrate because of a smaller pocket that normally accommodates the acetamido group of Neu5Ac in sialidases. A sialic acid with a hydroxyl in place of an acetamido group is 2-keto-3-deoxynononic acid (KDN). We show that KDN is the preferred substrate for the A. fumigatus sialidase and that A. fumigatus can utilize KDN as a sole carbon source. A 1.45-Å resolution crystal structure of the enzyme in complex with KDN reveals KDN in the active site in a boat conformation and nearby a second binding site occupied by KDN in a chair conformation, suggesting that polyKDN may be a natural substrate. The enzyme is not inhibited by the sialidase transition state analog 2-deoxy-2,3-dehydro-N-acetylneuraminic acid (Neu5Ac2en) but is inhibited by the related 2,3-didehydro-2,3-dideoxy-D-glycero-D-galacto-nonulosonic acid that we show bound to the enzyme in a 1.84-Å resolution crystal structure. Using a fluorinated KDN substrate, we present a 1.5-Å resolution structure of a covalently bound catalytic intermediate. The A. fumigatus sialidase is therefore a KDNase with a similar catalytic mechanism to Neu5Ac exosialidases, and this study represents the first structure of a KDNase.

sialic acid, protein structure, Kdn, sialidase, X-ray crystallography, enzyme structure, Aspergillus, Carbohydrate Metabolism, KDNase

NCBI PubMed ID: 21247893
Publication DOI: 10.1074/jbc.M110.207043
Journal NLM ID: 2985121R
Publisher: Baltimore, MD: American Society for Biochemistry and Molecular Biology
Correspondence: Telford JC
Institutions: Biomedical Sciences Research Complex, University of St. Andrews, St. Andrews, United Kingdom, Departments of Biological Sciences and Chemistry, Simon Fraser University, Burnaby, Canada, Institute for Glycomics, Griffith University, Queensland, Australia, Department of Pharmacy and Pharmacology, University of Bath, Bath, United Kingdom
Methods: cell growth

Ganoderma, a genus of polypore white rot fungus with some species such as G. lucidum and G. sinense have been reported with remarkable biological activities and used as traditional medicine for long. On the other hand, G. boninense is recognized as an important oil palm pathogen which causes intensive losses in oil palm industry. Hence, this study reveals the potential of antimicrobial properties of G. boninense fruiting bodies extract using different solvents. Ethyl acetate extract demonstrated a broad spectrum pathogens inhibition activity, followed by hot water > acetone > methanol > ethanol > chloroform. Ethyl acetate extract also shown the strongest growth inhibition against Proteus mirabilis (14.20 ± 0.40 mm). Lowest MIC (0.625 mg/ml) was observed in methanol extract against Coagulase-Negative Staphylococci. LC-MS analysis identified the extracts of G. boninense putatively contains natural occurring derivatives of alkaloid, fatty acid, heterocyclic compounds and glycosides. G. boninense may potential as the future drug. However, further investigation is required to understand this fungus in depth.

pathogenic bacteria, antimicrobial, natural compounds, Ganoderma boninense

Publication DOI: 10.22207/JPAM.14.2.16
Journal NLM ID: 101310551
Publisher: Bhopal, India: M.N. Khan
Correspondence: chongkp@ums.edu.my
Institutions: Faculty of Science and Natural Resources, Universiti Malaysia Sabah, Jalan UMS, Kota Kinabalu, Malaysia, FGV Chair of Sustainable Oil Palm Management, Faculty of Sustainable Agriculture, Universiti Malaysia Sabah, Sandakan, Malaysia
Methods: PCR, DNA sequencing, extraction, cell growth, DNA extraction, evaporation, antimicrobial assay, filtration, UPLC-QTOF-MS