title: Specificity and affinity of natural product cyclopentapeptide inhibitors against A. fumigatus, human, and bacterial chitinases.
abstract: Family 18 chitinases play key roles in organisms ranging from bacteria to man. There is a need for specific, potent inhibitors to probe the function of these chitinases in different organisms. Such molecules could also provide leads for the development of chemotherapeuticals with fungicidal, insecticidal, or anti-inflammatory potential. Recently, two natural product peptides, argifin and argadin, have been characterized, which structurally mimic chitinase-chitooligosaccharide interactions and inhibit a bacterial chitinase in the nM-mM range. Here, we show that these inhibitors also act on human and Aspergillus fumigatus chitinases. The structures of these enzymes in complex with argifin and argadin, together with mutagenesis, fluorescence, and enzymology, reveal that subtle changes in the binding site dramatically affect affinity and selectivity. The data show that it may be possible to develop specific chitinase inhibitors based on the argifin/argadin scaffolds.
authors.affiliation: Division of Biological Chemistry & Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland.
authors.forename: Francesco V
authors.initials: FV
authors.lastname: Rao
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Houston
authors.forename: Rolf G
authors.initials: RG
authors.lastname: Boot
authors.forename: Johannes M F G
authors.initials: JM
authors.lastname: Aerts
authors.forename: Michael
authors.initials: M
authors.lastname: Hodkinson
authors.forename: David J
authors.initials: DJ
authors.lastname: Adams
authors.forename: Kazuro
authors.initials: K
authors.lastname: Shiomi
authors.forename: Satoshi
authors.initials: S
authors.lastname: Omura
authors.forename: Daan M F
authors.initials: DM
authors.lastname: van Aalten
mesh_terms: D001232:Aspergillus fumigatus / Q000187:drug effects / Q000201:enzymology*; D001419:Bacteria / Q000187:drug effects / Q000201:enzymology*; D001667:Binding, Competitive; D002241:Carbohydrates / Q000737:chemistry / Q000494:pharmacology; D002688:Chitinases / Q000037:antagonists & inhibitors* / Q000737:chemistry* / Q000145:classification; D003001:Cloning, Molecular; D015195:Drug Design; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D006801:Humans; D006860:Hydrogen Bonding; D007700:Kinetics; D008297:Male; D018716:Molecular Mimicry; D008969:Molecular Sequence Data; D015394:Molecular Structure; D010456:Peptides, Cyclic / Q000737:chemistry / Q000494:pharmacology*; D017434:Protein Structure, Tertiary; D013329:Structure-Activity Relationship; D013379:Substrate Specificity
chemical_list: D002241:Carbohydrates; D004791:Enzyme Inhibitors; D010456:Peptides, Cyclic; C419444:argadin; C413566:argifin; D002688:Chitinases