Candida albicans cell wall as a target of action for the protein\u2013carbohydrate fraction from coelomic fluid of Dendrobaena veneta

Marta J Fiołka,Kinga Lewtak,Sylwia Mieszawska,Katarzyna Stępnik,Aneta Szymańska,Paulina Czaplewska,Tomasz Buchwald,Weronika Sofińska-Chmiel

doi:10.1038/s41598-020-73044-w

Abstract

The protein–polysaccharide fraction (AAF) isolated from the coelomic fluid of the earthworm Dendrobaena veneta destroys C. albicans cells by changing their morphology, disrupting cell division, and leading to cell death. Morphological changes in C. albicans cells induced by treatment with AAF were documented using DIC, SEM, and AFM. Congo Red staining showed that the fungal wall structure was changed after incubation with AAF. The effect on C. albicans cell walls was shown by AFM analysis of the surface roughness of fungal cell walls and changes in the wall thickness were visualized using Cryo-SEM. The FTIR analysis of C. albicans cells incubated with AAF indicated attachment of protein or peptide compounds to the fungal walls. The intact LC–ESI–MS analysis allowed accurate determination of the masses of molecules present in AAF. As shown by the chromatographic study, the fraction does not cross biological membranes. The Cryo-TEM analysis of AAF demonstrated the ability of smaller subunits to combine into larger agglomerates. AAF is thermally stable, which was confirmed by Raman spectroscopy. AAF can be considered as a potential antifungal antibiotic with activity against clinical C. albicans strains.

Highlights

The protein–polysaccharide fraction (AAF) isolated from the coelomic fluid of the earthworm Dendrobaena veneta destroys C. albicans cells by changing their morphology, disrupting cell division, and leading to cell death
The aim of the present study was to explore the mechanism of a protein–carbohydrate fraction from D. veneta Coelomic fluid (CF) on a clinical C. albicans strain and provide further chemical characterization of the fraction
Compounds of natural origin are a source of various chemical structures often showing the desired biological activity[16]. They form a structurally privileged group in the process of binding to specific enzymes, receptors, or other binding sites and in this way show high affinity for structures found in living organisms

Summary

Introduction

The protein–polysaccharide fraction (AAF) isolated from the coelomic fluid of the earthworm Dendrobaena veneta destroys C. albicans cells by changing their morphology, disrupting cell division, and leading to cell death. As shown in numerous reports of world health organizations, recent decades have been characterized by an increase in the rates of invasive fungal infection. This is mainly related to the growing population at risk of infection, which includes immunocompromised patients with cancers and those with human immunodeficiency virus HIV. C. albicans is the third most common pathogen causing intensive-care unit infections and the second cause of vulvovaginal c andidiasis[13] It is isolated most frequently from samples in urinary tract or glans penis infections[7,13]. There is a rising number of C. albicans strains with resistance to antifungal drugs, e.g. fluconazoles, azoles, and e chinocandins[2,11]

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