Triintsin, a human pathogenic fungus-derived defensin with broad-spectrum antimicrobial activity

Since there is a symbiotic and competitive relationship between microorganisms in the same ecological niche, fungal defensins have been found to be important resources for antimicrobial peptides. Here, a fungal defensin, triintsin, was characterized in a clinical isolate of Trichophyton interdigitale from a patient with onychomycosis. The comparison of its genomic and mRNA sequences showed the gene organization and structure of three coding exons separated by two introns. The precursor peptide of triintsin contained 85 amino acid residues, which were composed of three parts including an N-terminal signal domain of 21 residues, a pro-peptide of 47 residues that ended at lysine-arginine and a mature peptide of 38 residues at the C-terminus. The 3D-structure established by homology modeling revealed that triintsin presented a representative typical cysteine-stabilized α-helical and β-sheet fold. The reductive linear peptide of triintsin was obtained by chemical synthesis. After cyclization to form three pairs of disulfide bonds, the oxidative-type peptide displayed broad-spectrum antimicrobial activity against both gram-positive and gram-negative bacteria but also showed anti-fungal activity. Moreover, triintsin can effectively inhibit the growth of clinical strains. Altogether, the peptide is a human pathogenic fungus-derived defensin with broad-spectrum antimicrobial activity.

De novo production of metabolites by fungal co-culture of Trichophyton rubrum and Bionectria ochroleuca

The co-cultivation of fungi has recently been described as a promising strategy to induce the production of novel metabolites through possible gene activation. A large screening of fungal co-cultures in solid media has identified an unusual long-distance growth inhibition between Trichophyton rubrum and Bionectria ochroleuca. To study metabolite induction in this particular fungal interaction, differential LC-MS-based metabolomics was performed on pure strain cultures and on their co-cultures. The comparison of the resulting fingerprints highlighted five de novo induced compounds, which were purified using software-oriented semipreparative HPLC-MS. One metabolite was successfully identified as 4″-hydroxysulfoxy-2,2″-dimethylthielavin P (a substituted trimer of 3,5-dimethylorsellinic acid). The nonsulfated form, as well as three other related compounds, were found in the pure strain culture of B. ochroleuca.

Role of the ABC transporter TruMDR2 in terbinafine, 4-nitroquinoline N-oxide and ethidium bromide susceptibility in Trichophyton rubrum

A single-copy gene, designated TruMDR2, encoding an ATP-binding cassette (ABC) transporter was cloned and sequenced from the dermatophyte Trichophyton rubrum. The ORF of TruMDR2 was 4048 nt and the deduced amino acid sequence showed high homology with ABC transporters involved in drug efflux in other fungi. The encoded ABC protein predicted 12 transmembrane segments (TMSs) and two almost identical nucleotide-binding domains (NBDs) arranged in two halves in a (TMS(6)-NBD)(2) configuration and could be classified as a member of the multidrug-resistance (MDR) class of ABC transporters. Northern blot analyses revealed an increased level of transcription of the TruMDR2 gene when mycelium was exposed to acriflavine, benomyl, ethidium bromide, ketoconazole, chloramphenicol, griseofulvin, fluconazole, imazalil, itraconazole, methotrexate, 4-nitroquinoline N-oxide (4NQO) or tioconazole. Disruption of the TruMDR2 gene rendered the mutant more sensitive to terbinafine, 4NQO and ethidium bromide than the control strain, suggesting that this transporter plays a role in modulating drug susceptibility in T. rubrum.

White variants of Trichophyton violaceum isolated in Ethiopia

Certain dermatophytes are geographically restricted and endemic in particular parts of the world, while other species may have a sporadic but worldwide distribution. Trichophyton violaceum is one of the most common dermatophytes causing tinea capitis, and is the predominant cause of tinea in Africa, South America and the Indian subcontinent. Among 1187 dermatophyte isolates collected from Ethiopian patients with various types of tinea, 32 isolates had uncharacteristic phenotypic features. Based on conventional methods complemented by sequence analysis of the rDNA ITS2 region, these isolates were identified as white variants of T. violaceum. This is the first time that white isolates of T. violaceum have been identified in Ethiopia.

Isolation and characterization of an immunogenic fragment of heat shock protein 60 from Trichophyton mentagrophytes. Isolierung und Charakterisierung eines immunogenen Fragmentes des Hitzeschockproteins 60 von Trichophyton mentagrophytes

Heat shock protein 60 (hsp60) were isolated from several fungal, protozoal and many bacterial pathogens and successfully used for protective vaccination in some infection models. This work focuses on the isolation of recombinant hsp60 from the dermatophyte, Trichophyton mentagrophytes as a potentially protective antigen in trichophytosis. With the help of a previously tested set of degenerated primers, it was used reverse transcriptase polymerase chain reaction (RT-PCR) for isolation of partial cDNA of the hsp60 T. mentagrophytes (labelled hsp60-TM814), which was cloned into cloning vector. The sequencing of hsp60-TM814 cDNA and global alignment confirmed homology of the hsp60-TM814 with other members of the hsp60 family. Hsp60-TM814 cDNA corresponds to the region encoding the immunoprotective fragment of the hsp60 from Histoplasma capsulatum, used successfully in mouse model of histoplasmosis. A recombinant fragment (r-hsp60-TM664), 220 amino acids in length, was prepared in a prokaryote expression system, and its identity confirmed by mass spectroscopy. High immunogenicity of r-hsp60-TM664 was proven after subcutaneous immunization of mice. Immunized mouse sera recognized r-hsp60-TM664 on Western blots as well as hsp60 from mouse liver lysate and lysate of Candida albicans.

A highly efficient synthesis of an octasaccharide, the repeating unit of the cell-wall mannan of Trichophyton mentagrophytes and T. rubrum

A highly concise and effective synthesis of the mannose octasaccharide repeating unit of the cell-wall mannan of Trichophyton mentagrophytes and T. rubrum was achieved via 6-O-glycosylation of a tetrasaccharide acceptor with a tetrasaccharide donor, followed by deprotection. The key tetrasaccharide (11) was constructed by selective 6-O-glycosylation of allyl 3,4-di-O-benzoyl-alpha-D-mannopyranosyl-(1-->6)-2,3,4-tri-O-benzoyl-alpha-D-mannopyranoside with 6-O-acetyl-2,3,4-tri-O-benzoyl-alpha-D-mannopyranosyl trichloroacetimidate, then with 2,3,4,6-tetra-O-benzoyl-alpha-D-mannopyranosyl trichloroacetimidate. The tetrasaccharide acceptor (13) was obtained by selective 6-O-deacetylation of 11, while the tetrasaccharide donor 12 was obtained by deallylation of 11, followed by trichloroacetimidation.

Isolation of total RNA from dermatophytes

We report a method for the preparation of total RNA from the anthropophilic dermatophyte Trichophyton rubrum. To generate large quantities of mycelia, the fungus was grown in liquid culture medium. The harvested mycelial mass was ground to a fine powder in liquid nitrogen and homogenized in guanidine isothiocyanate buffer followed by ultracentrifugation of the obtained suspension through a caesium chloride gradient. Analysis of the prepared RNA showed two prominent ribosomal RNA (rRNA) bands of about 3.36 and 1.82 kb. Northern blot hybridization with a beta-actin cDNA confirmed the high quality of the fungal mRNA. Successful isolation of RNA from two other dermatophyte species, namely Trichophyton mentagrophytes and Microsporum canis, demonstrated the general applicability of the described procedure.

Characterization of fungal spores by laser desorption/ionization time-of-flight mass spectrometry

A considerable volume of research has now been completed on the application of matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) to the analysis of bacteria; however, to date no definitive studies have been made using this technique on fungi. Preliminary studies on the application of the MALDI-MS methodology, previously developed for the analysis of bacteria, to the analysis of intact fungal spores are described here. MALDI-MS and electrospray mass spectrometry enable the high molecular weight analysis of proteins, glycoproteins, oligosaccharides and oligonucleotides. Using MALDI-MS with bacteria has demonstrated the ability to produce 'fingerprints' of the intact cells with the ions observed being associated with the proteinaceous components of the cell wall. This paper reports the adaptation of this technique to the direct analysis of fungal cells. The high percentage of carbohydrate in the fungal cell wall indicates that the ions observed in the mass spectrometric experiments may be of carbohydrate origin. Penicillium spp., Scytalidium dimidiatum and Trichophyton rubrum have been studied in this preliminary investigation and all show individually distinctive spectra which would appear to provide a profile of the cellular material with discrete peaks being observed over the mass range 2 to 13 kDa. The spectra obtained are reproducible within the method used but, as shown in our previous studies on bacteria, washing may selectively release components from the fungal cell wall.

NMR assignment of the galactomannan of Candida lipolytica

The chemical structure of the cell wall galactomannan of Candida lipolytica was analyzed using two-dimensional NMR techniques without chemical fragmentation. The H-1-H-2-correlated cross-peaks of the galactomannan indicated that it consists of an alpha-1,6-linked mannan backbone moiety with side chains. A sequential NMR assignment of the side chains through nuclear Overhauser effect (NOE) cross-peaks indicated that the triose side chain contains an alpha-1,2-linked galactopyranose unit at the non-reducing terminal. The structure was significantly different from the galactomannan of Trichophyton. The molar ratio of the side chains calculated from the H-1 signal dimensions indicated that ca. 45% of the backbone alpha-1,6-linked mannose units are not substituted with side chains and are responsible for the reactivity of the galactomannan with factor 9 serum.

NMR study of the galactomannans of Trichophyton mentagrophytes and Trichophyton rubrum

Around 90% of chronic dermatophyte infections are caused by the fungi Trichophyton mentagrophytes and Trichophyton rubrum. One of the causes of the chronic infection resides in the immunosuppressive effects of the cell-wall components of these organisms. Therefore we have attempted to identify the chemical structure of galactomannan, one of the major cell-wall components. The cell-wall polysaccharides secreted by T. mentagrophytes and T. rubrum were isolated from the culture medium and fractionated into three subfractions by DEAE-Sephadex chromatography. Analysis of each subfraction by NMR indicated that there are two kinds of polysaccharides present, i.e. mannan and galactomannan. The mannan has a linear backbone consisting of alpha1,6-linked mannose units, with alpha1,2-linked mannose units as side chains. The core mannan moiety of the galactomannan was analysed by a sequential NMR assignment method after removing the galactofuranose units by acid treatment. The result indicates that the mannan moiety has a linear repeating structure of alpha1,2-linked mannotetraose units connected by an alpha1,6 linkage. The H-1 signals of the two intermediary alpha1, 2-linked mannoses of the tetraose unit showed a significant upfield shift (Deltadelta=0.05-0.08 p.p.m.), due to the steric effect of an alpha1,6-linked mannose unit. The attachment point of the galactofuranose units was determined at C-3 of the core mannan by the assignment of the downfield-shifted 13C signals of the galactomannan compared with those of the acid-modified product. In these galactomannans there were no polygalactofuranosyl chains which have been found in Penicillium charlesii and Aspergillus fumigatus.

Human nail dust: hazard to chiropodists or merely nuisance?

This survey was carried out in response to anxiety among chiropodists as earlier reports had raised the possibility of respiratory damage as a result of sensitization to trichophytons. Questionnaires were sent to 327 chiropodists and 168 replies were received. The aim was to investigate respiratory symptoms and their relationship to work and drill usage. All of those completing questionnaires were invited to attend the occupational health department for prick tests and lung function tests. Just over one half of those who were invited attended. Although upper respiratory symptoms were common, only eye symptoms and wheeze were significantly more prevalent in those who used non-vacuum drills. Nasal symptoms were commoner in those who had spent less than ten years in the profession. Throat symptoms and multiple symptoms occurred more commonly in the 17 per cent of attenders who had positive prick tests to trichophytons. There were no cases of occupational asthma and no definite relationship between any symptom and work. It was confirmed that sensitization to trichophytons was common (16.5 per cent) but did not produce chest problems. Nail dust might produce symptoms by simple irritation of the upper respiratory tract.

Phosphoglycerides of Trichophyton terrestre and one phenotype selected from the Apollo 16 microbial ecology evaluation device

Total lipid extracted from wild-type Trichophyton terrestre CDC-X285 was found to be 2.0 percent of the dry cell weight. The total lipid contained the following phospholipid components identified by silicic acid-impregnated thin-layer and paper chromatography: phosphatidyl inositol, phosphatidyl choline, phosphatidyl serine, and phosphatidic acid. The total lipid extracted from the phenotype T. terrestre 7048-1 isolated from the Apollo 16 Microbial Ecology Evaluation Device (MEED) was found to vary according to the time at which the phospholipids were extracted. The Trichophyton phenotype was selected from a cuvette housed in the MEED exposed to specific space parameters including ultraviolet light of known wavelengths and energy levels in deep space. The phospholipid components, identified in the phenotype were phosphatidyl ethanolamine and cardiolipin. The major lipid fraction was composed of digalactosyl diglyceride and monogalactosyl diglyceride. An unusual lipid was detected in the phenotype, which appeared to be sterol glycoside.