Project description:The human gut is inhabited by a complex ecosystem of microorganisms, encompassing bacteria, viruses, protozoa, and fungi. Recent research has illuminated the significance of the gut fungal microbiota (mycobiota) in shaping host immunity and influencing the onset and progression of various human diseases. While most investigations into gut microbiota have centered on bacteria, accumulating evidence has underscored the role of mycobiota in the development of inflammatory bowel diseases (IBD), including both ulcerative colitis (UC) and Crohn's disease (CD). In this study, we present the isolation of the live Malassezia globosa strains from the intestinal mucosa of UC patients for the first time. We provide a comprehensive analysis of the characteristics and virulence of this fungus. Malassezia, primarily known to inhabit human skin, prompted us to compare the genomes, transcriptomes, and virulence of M. globosa gut isolates with those of M. globosa strains isolated from the skin. This comparative analysis aimed to discern potential niche-specific adaptations of the fungus. Our findings reveal a striking disparity in the pathogenicity of M. globosa isolated from the gut compared to its skin counterpart. In a mouse model, gut-isolated M. globosa exhibited a more pronounced exacerbation of DSS-induced colitis and elevated production of inflammatory cytokines. Additionally, transcriptome analysis indicated that gut isolates of M. globosa display heightened sensitivity to normoxia compared to their skin-isolated counterparts, suggesting adaptation to the hypoxic conditions prevalent in the intestinal mucosal environment
Project description:The skin barrier is vital for protection against environmental threats including insults caused by skin-resident microbes. Dysregulation of this barrier is a hallmark of atopic dermatitis (AD) and ichthyosis, with variable consequences for host immune control of colonizing commensals and opportunistic pathogens. While Malassezia is the most abundant commensal fungus of the skin, little is known about the host control of this fungus in inflammatory skin diseases. Here we show that in barrier-impaired skin, Malassezia acquires enhanced fitness and overt growth properties. By using four distinct and complementary murine models of atopic dermatitis and ichthyosis we provide evidence that structural and metabolic changes in the dysfunctional epidermal barrier environment provide increased accessibility and an altered lipid profile, to which the lipid-dependent yeast adapts for enhanced nutrient assimilation. These findings reveal fundamental insights into the implication of the mycobiota in the pathogenesis of common skin barrier disorders.
Project description:During mammalian colonization and infection, microorganisms must be able to rapidly sense and adapt to changing environmental conditions including alterations in extracellular pH. The fungus-specific Rim/Pal signaling pathway is one process that supports microbial adaptation to alkaline pH. This cascading series of interacting proteins terminates in the proteolytic activation of the highly conserved Rim101/PacC protein, a transcription factor that mediates microbial responses that favor survival in neutral/alkaline pH growth conditions, including many mammalian tissues. We identified the putative Rim pathway proteins Rim101 and Rra1 in the human skin colonizing fungus Malassezia sympodialis. Targeted mutation of these proteins confirmed their role in M. sympodialis growth at higher pH. Additionally, comparative transcriptional analysis of the mutant strains compared to wild-type suggested mechanisms for fungal adaptation to alkaline conditions. These signaling proteins are required for optimal growth in a murine model of atopic dermatitis, a pathological condition associated with increased skin pH. Together these data elucidate both conserved and phylum-specific features of microbial adaptation to extracellular stresses.
Project description:The skin commensal yeast Malassezia is associated with several skin disorders. To establish a reference resource, we sought to determine the complete genome sequence of Malassezia sympodialis and identify its protein-coding genes. A novel genome annotation workflow combining RNA sequencing, proteomics, and manual curation was developed to determine gene structures with high accuracy.
Project description:Malassezia species are lipophilic and lipid dependent yeasts belonging to the human and animal microbiota. Typically, they are isolated from regions rich in sebaceous glands. They have been associated with dermatological diseases such as seborrheic dermatitis, tinea versicolor, atopic dermatitis, and folliculitis. Genome sequences of Malassezia globosa, Malassezia sympodialis, and Malassezia pachydermatis lack genes related to fatty acid synthesis. Here, lipid synthesis pathways of M. furfur, M. pachydermatis, M. globosa, M. sympodialis and an atypical variant of M. furfur were reconstructed using genome data and Constraints Based Reconstruction and Analysis. The metabolic reconstruction allowed us to predict variation in the fluxes of each reaction over the network to satisfy the biomass objective function. Proteomic profiling improved and validated the models through data integration. Results suggest that several mechanisms including steroid and butanoate metabolism explain the yeast’s growth under different lipid conditions. Flux differences were observed in production of riboflavin in M. furfur and the biosynthesis of glycerolipids in the atypical variant of M. furfur and Malassezia sympodialis.
Project description:Introduction. Malassezia globosa is a yeast species that belongs to the mycobiota of humans and animals, associated with dermatological disorders, such as dandruff. This is a chronic scalp skin disorder characterized by flaking and itching. Treatments include commercial shampoo with different formulations that contain antifungal activities like zinc pyrithione (ZPT) or piroctone olamine (PO). The effectiveness of these formulations has been evaluated for decades for dandruff symptom relief of volunteers. To date, non-mammalian, in vivo methods exist to test formulations of these actives. Aim. To evaluate in vivo in Galleria mellonella larva, two commercial antifungal shampoos (shampoo with 1 % ZPT and 1.6 % zinc Carbonate and shampoo with 0.5 % PO) against this species. Methodology. G. mellonella larvae were inoculated with M. globosa on abraded cuticular surface. Then, integument cell viability, histological changes, and fungal burden were evaluated. Results. Larvae inoculated with M. globosa showed higher lesion melanization and tissue damage. In addition, M. globosa population showed to increase over time. Concerning the shampoo's effectiveness, both formulations significantly reduced M. globosa burden and tissue damage. Conclusion. G. mellonella larvae were allowed to evaluate M. globosa superficial infection and antifungal effectiveness. Shampoos with ZPT and PO showed a positive effect on inoculated larvae.
Project description:Malassezia globosa cytochromes P450 CYP51 and CYP5218 are sterol 14α-demethylase (the target of azole antifungals) and a putative fatty acid metabolism protein (and a potential azole drug target), respectively. Lanosterol, eburicol and obtusifoliol bound to CYP51 with Kd values of 32, 23 and 28 μM, respectively, catalyzing sterol 14α-demethylation with respective turnover numbers of 1.7 min(-1), 5.6 min(-1) and 3.4 min(-1). CYP5218 bound a range of fatty acids with linoleic acid binding strongest (Kd 36 μM), although no metabolism could be detected in reconstitution assays or role in growth on lipids. Clotrimazole, fluconazole, itraconazole, ketoconazole, voriconazole and ketaminazole bound tightly to CYP51 (Kd ≤ 2 to 11 nM). In contrast, fluconazole did not bind to CYP5218, voriconazole and ketaminazole bound weakly (Kd ~107 and ~12 μM), whereas ketoconazole, clotrimazole and itraconazole bound strongest to CYP5218 (Kd ~1.6, 0.5 and 0.4 μM) indicating CYP5218 to be only a secondary target of azole antifungals. IC50 determinations confirmed M. globosa CYP51 was strongly inhibited by azole antifungals (0.15 to 0.35 μM). MIC100 studies showed itraconazole should be considered as an alternative to ketoconazole given the potency and safety profiles and the CYP51 assay system can be used in structure-activity studies in drug development.
Project description:Diacylglycerol (DAG)-like lipases are found to play an important role in the life sciences and industrial fields. A putative DAG-like lipase (MgMDL2) from Malassezia globosa was cloned and expressed in recombinant Pichia pastoris. The recombinant MgMDL2 was expressed as a glycosylated protein and purified into homogeneity by anion exchange chromatography. The activity of recombinant MgMDL2 was optimal at 15 °C and pH 6.0, and it keeps over 50% of relative activity at 5 °C, suggesting that MgMDL2 was a cold active lipase. MgMDL2 retained over 80% of initial activity after incubation at 30 and 40 °C for 2.5 h, but it was not stable at 50 °C. Incubation of methanol and ethanol at a concentration of 30% for 2 h did not affect the recombinant enzyme activity, while metal ions, including Ca2+, Mn2+ and Ni2+, sharply inhibited the MgMDL2 activity at 5 mM by 42%, 35% and 36%, respectively. MgMDL2 exhibited a preference for medium chain-length esters with highest activity toward p-nitrophenyl caprylate, while it was active on mono- and diacylglycerol but not on triacylglycerol, indicating that it was a typical DAG-like lipase. By homology modeling, Phe278 was predicted to be involved in the preference of MgMDL2 for monoacyl- and diacyl-glyceride substrates, but not triglycerides.