title: Inhibition of Leishmania infantum trypanothione reductase by azole-based compounds: a comparative analysis with its physiological substrate by X-ray crystallography.
abstract: Herein we report a study aimed at discovering a new class of compounds that are able to inhibit Leishmania donovani cell growth. Evaluation of an in-house library of compounds in a whole-cell screening assay highlighted 4-((1-(4-ethylphenyl)-2-methyl-5-(4-(methylthio)phenyl)-1H-pyrrol-3-yl)methyl)thiomorpholine (compound 1) as the most active. Enzymatic assays on Leishmania infantum trypanothione reductase (LiTR, belonging to the Leishmania donovani complex) shed light on both the interaction with, and the nature of inhibition by, compound 1. A molecular modeling approach based on docking studies and on the estimation of the binding free energy aided our rationalization of the biological data. Moreover, X-ray crystal structure determination of LiTR in complex with compound 1 confirmed all our results: compound 1 binds to the T(SH)2 binding site, lined by hydrophobic residues such as Trp21 and Met113, as well as residues Glu18 and Tyr110. Analysis of the structure of LiTR in complex with trypanothione shows that Glu18 and Tyr110 are also involved in substrate binding, according to a competitive inhibition mechanism.
authors.affiliation: Dipartimento di Scienze Biochimiche, Sapienza Università di Roma, Piazzale A. Moro 5, 00185 Roma, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Baiocco
authors.forename: Giovanna
authors.initials: G
authors.lastname: Poce
authors.forename: Salvatore
authors.initials: S
authors.lastname: Alfonso
authors.forename: Martina
authors.initials: M
authors.lastname: Cocozza
authors.forename: Giulio Cesare
authors.initials: GC
authors.lastname: Porretta
authors.forename: Gianni
authors.initials: G
authors.lastname: Colotti
authors.forename: Mariangela
authors.initials: M
authors.lastname: Biava
authors.forename: Francesca
authors.initials: F
authors.lastname: Moraca
authors.forename: Maurizio
authors.initials: M
authors.lastname: Botta
authors.forename: Vanessa
authors.initials: V
authors.lastname: Yardley
authors.forename: Annarita
authors.initials: A
authors.lastname: Fiorillo
authors.forename: Antonella
authors.initials: A
authors.lastname: Lantella
authors.forename: Francesco
authors.initials: F
authors.lastname: Malatesta
authors.forename: Andrea
authors.initials: A
authors.lastname: Ilari
mesh_terms: D000981:Antiprotozoal Agents / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D001393:Azoles / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D016923:Cell Death / Q000187:drug effects; D018360:Crystallography, X-Ray; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D006801:Humans; D007624:KB Cells; D018314:Leishmania infantum / Q000187:drug effects* / Q000201:enzymology*; D008958:Models, Molecular; D015394:Molecular Structure; D009247:NADH, NADPH Oxidoreductases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D021261:Parasitic Sensitivity Tests; D013329:Structure-Activity Relationship
chemical_list: D000981:Antiprotozoal Agents; D001393:Azoles; D004791:Enzyme Inhibitors; D009247:NADH, NADPH Oxidoreductases; C049608:trypanothione reductase