title: Mechanism of inhibition of botulinum neurotoxin type A light chain by two quinolinol compounds.
abstract: Quinolinol-based compounds are a promising starting point for discovery of effective inhibitors of the clostridial neurotoxin, botulinum neurotoxin type A light chain (BoNT/A LC). Insights into the mechanism of inhibition by quinolinol compounds facilitate interpretation of docking data and inhibitor optimization. In this study, a fluorogenic substrate of BoNT/A, SNAPtide, was used to study the mechanism by which two new quinolinol compounds, MSU58 and MSU84, with IC50values of 3.3 μM and 5.8 μM, respectively, inhibit BoNT/A LC. Kinetic studies and model discrimination analysis showed both compounds to be competitive inhibitors of BoNT/A LC with inhibition constants (KI) 3.2 μM and 6.2 μM for MSU58 and MSU84, respectively. These data indicate that the inhibitors bind in the BoNT/A LC active site and that inhibitor binding is mutually exclusive with the binding of the substrate. This is the first study to report the competitive inhibition of BoNT/A LC by quinolinol compounds. These data help define the inhibitor binding pocket and, along with structure activity relationship studies, provide immediate direction for further compound synthesis.
authors.affiliation: Department of Chemistry and Biochemistry, Montclair State University, Montclair, NJ, 07043, USA.
authors.forename: Yacoba V T
authors.initials: YV
authors.lastname: Minnow
authors.affiliation: Department of Chemistry and Biochemistry, Montclair State University, Montclair, NJ, 07043, USA.
authors.forename: Ronald
authors.initials: R
authors.lastname: Goldberg
authors.affiliation: Department of Chemistry and Biochemistry, Montclair State University, Montclair, NJ, 07043, USA.
authors.forename: Sreedhar R
authors.initials: SR
authors.lastname: Tummalapalli
authors.affiliation: Department of Chemistry and Biochemistry, Montclair State University, Montclair, NJ, 07043, USA.
authors.forename: David P
authors.initials: DP
authors.lastname: Rotella
authors.affiliation: Department of Chemistry and Biochemistry, Montclair State University, Montclair, NJ, 07043, USA. Electronic address: goodeyn@mail.montclair.edu.
authors.forename: Nina M
authors.initials: NM
authors.lastname: Goodey
mesh_terms: D001667:Binding, Competitive; D019274:Botulinum Toxins, Type A / Q000037:antagonists & inhibitors* / Q000737:chemistry; D002384:Catalysis; D020134:Catalytic Domain; D006912:Hydroxyquinolines / Q000737:chemistry*; D020128:Inhibitory Concentration 50; D007700:Kinetics; D008027:Light; D010455:Peptides / Q000737:chemistry; D011485:Protein Binding; D011994:Recombinant Proteins / Q000737:chemistry; D013329:Structure-Activity Relationship; D014867:Water / Q000737:chemistry; D015032:Zinc / Q000737:chemistry
chemical_list: D006912:Hydroxyquinolines; D010455:Peptides; D011994:Recombinant Proteins; D014867:Water; D019274:Botulinum Toxins, Type A; D015032:Zinc
keywords: Botulinum; Competitive inhibitor; FRET peptide; Fluorescence quenching; Neurotoxin; Quinolinol