Proteomic Characterization of Aspergillus fumigatus Treated with an Antifungal Coumarin for Identification of Novel Target Molecules of Key Pathways

Abstract

A synthetic coumarin, N,N,N-triethyl-11-(4-methyl-2-oxo-2H-chromen-7-yloxy)-11-oxoundecan-1-aminium bromide (SCD-1), having potent activity against pathogenic Aspergilli (MIC90 15.62 μg/mL), was investigated to identify its molecular targets in the pathogen. The proteome of Aspergillus fumigatus was developed after treatment with sublethal doses of compound and analyzed. The results demonstrated 143 differentially expressed proteins on treatment with SCD-1. The expression of four proteins, namely cell division control protein, ubiquitin-like activating enzyme, vacuolar ATP synthase catalytic subunit A, and UTP-glucose-1-phosphate uridylyltransferase of A. fumigatus, was completely inhibited, whereas there were 13 newly expressed and 96 overexpressed proteins, mainly belonging to stress pathway. The treatment of A. fumigatus with SCD-1 also led to attenuation of proteins involved in cell replication and other important biosynthetic processes, including riboflavin biosynthesis, which has been pathogen-specific. In addition to key enzymatic players and antioxidants, nine hypothetical proteins were also identified, seven of which have been novel, being described for the first time. As no cellular functions have yet been described for these hypothetical proteins, their alteration in response to SCD-1 provides significant information about their putative roles in pathogen defense.

In Vivo Efficacy of a Synthetic Coumarin Derivative in a Murine Model of Aspergillosis

“…Till date, there have been no reports on the toxicity and in vivo antifungal activity of coumarins. We have previously reported the in vitro antifungal activity of SCD-1 [23], and its impact on the proteomic machinery of A. fumigatus [24]. The present study addressed for the first time the in vivo safety and antifungal efficacy of a synthetic coumarin derivative.…”

“…The compound exhibited potent activity against pathogenic Aspergilli (MIC 90 15.62 µg/mL) and the possible mechanism of action of SCD-1 was described using differential proteomics in our earlier report [24]. The treatment of A. fumigatus with SCD-1 resulted in complete inhibition of proteins belonging to key metabolic pathways of cell replication and also the riboflavin biosynthesis, which has been a pathogen-specific process [24]. The present study deals with evaluation of safety and antifungal efficacy of SCD-1 by using experimental animals.…”

“…It was synthesized in laboratory according to the procedure described in our earlier report [23]. In view of the promising in vitro antifungal activity, safety and significant impact on the proteomic machinery of A. fumigatus [24] the compound was considered to be an important candidate molecule, therefore, investigated for in vivo safety and antifungal efficacy in this study.…”

“…The investigations on synthetic coumarin derivatives (SCDs) led us to identify an antifungal molecule N , N , N -Triethyl-11-(4-methyl-2-oxo-2 H -benzopyran-7-yloxy)-11-oxoundecan-1-aminium bromide coded as SCD-1 [23]. The compound exhibited potent activity against pathogenic Aspergilli (MIC 90 15.62 µg/mL) and the possible mechanism of action of SCD-1 was described using differential proteomics in our earlier report [24]. The treatment of A. fumigatus with SCD-1 resulted in complete inhibition of proteins belonging to key metabolic pathways of cell replication and also the riboflavin biosynthesis, which has been a pathogen-specific process [24].…”

Proteomic analysis of Aspergillus fumigatus – clinical implications

“…Subsequently, the proteome of A. fumigatus following exposure to SCD-1 was investigated to dissect its antifungal mechanism [122]. Cytosolic proteins were extracted from germlings and analysed by 2-DE with LC-MS/MS identification.…”