title: An integrated approach for identification and target validation of antifungal compounds active against Erg11p.
abstract: Systemic life-threatening fungal infections represent a significant unmet medical need. Cell-based, phenotypic screening can be an effective means of discovering potential novel antifungal compounds, but it does not address target identification, normally required for compound optimization by medicinal chemistry. Here, we demonstrate a combination of screening, genetic, and biochemical approaches to identify and characterize novel antifungal compounds. We isolated a set of novel non-azole antifungal compounds for which no target or mechanism of action is known, using a screen for inhibition of Saccharomyces cerevisiae proliferation. Haploinsufficiency profiling of these compounds in S. cerevisiae suggests that they target Erg11p, a cytochrome P450 family member, which is the target of azoles. Consistent with this, metabolic profiling in S. cerevisiae revealed a buildup of the metabolic intermediates prior to Erg11p activity, following compound treatment. Further, human cytochrome P450 is also inhibited in in vitro assays by these compounds. We modeled the Erg11p protein based on the human CYP51 crystal structure, and in silico docking of these compounds suggests that they interact with the heme center in a manner similar to that of azoles. Consistent with these docking observations, Candida strains carrying azole-resistant alleles of ERG11 are also resistant to the compounds in this study. Thus, we have identified non-azole Erg11p inhibitors, using a systematic approach for ligand and target characterization.
authors.affiliation: Novartis Institutes for BioMedical Research, Novartis Campus, Basel, Switzerland. dominic.hoepfner@novartis.com
authors.forename: Dominic
authors.initials: D
authors.lastname: Hoepfner
authors.forename: Shantanu
authors.initials: S
authors.lastname: Karkare
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Helliwell
authors.forename: Martin
authors.initials: M
authors.lastname: Pfeifer
authors.forename: Markus
authors.initials: M
authors.lastname: Trunzer
authors.forename: Sophie
authors.initials: S
authors.lastname: De Bonnechose
authors.forename: Alfred
authors.initials: A
authors.lastname: Zimmerlin
authors.forename: Jianshi
authors.initials: J
authors.lastname: Tao
authors.forename: Daryl
authors.initials: D
authors.lastname: Richie
authors.forename: Andreas
authors.initials: A
authors.lastname: Hofmann
authors.forename: Stefan
authors.initials: S
authors.lastname: Reinker
authors.forename: Mathias
authors.initials: M
authors.lastname: Frederiksen
authors.forename: N Rao
authors.initials: NR
authors.lastname: Movva
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Porter
authors.forename: Neil S
authors.initials: NS
authors.lastname: Ryder
authors.forename: Christian N
authors.initials: CN
authors.lastname: Parker
mesh_terms: D000935:Antifungal Agents / Q000737:chemistry / Q000494:pharmacology*; D001393:Azoles / Q000494:pharmacology; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System; D025141:Drug Resistance, Fungal / Q000235:genetics; D057166:High-Throughput Screening Assays; D008826:Microbial Sensitivity Tests; D008958:Models, Molecular; D020836:Protein Structure, Quaternary; D012441:Saccharomyces cerevisiae / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000037:antagonists & inhibitors*
chemical_list: D000935:Antifungal Agents; D001393:Azoles; D065607:Cytochrome P-450 Enzyme Inhibitors; D029701:Saccharomyces cerevisiae Proteins; D003577:Cytochrome P-450 Enzyme System; C526348:Erg11 protein, S cerevisiae