Kazutoh Takesako

Transformation system for prototrophic industrial yeasts using the AUR1 gene as a dominant selection marker

We show a new transformation system for prototrophic yeast strains including those of Saccharomyces cerevisiae, Kluyveromyces lactis, K. marxianus, and Candida glabrata. This system is composed of an antibiotic, aureobasidin A (AbA), and its resistance gene AUR1‐C as a selection marker. Southern analysis of genomic DNAs of the transformants indicated that the copy number of the plasmid increased from one to more than four, depending on the concentration of AbA used for selection of the transformants. The AUR1‐C gene was also effective as a selection marker for gene disruption, and was able to disrupt both copies of the gene on homologous chromosomes of diploid cells by a single round of transformation. This system has a broad application in the transformation and gene disruption of prototrophic strains of a variety of yeast species.

Total synthesis of an antifungal cyclic depsipeptide aureobasidin A

Abstract The first total synthesis of antifungal cyclic depsipeptide aureobasidin A is described. The synthesis was achieved mainly using bromotris(pyrrolidino)phosphonium hexafluorophosphate (PyBroP) as a coupling reagent. Peptide cyclization was carried out between L- allo -isoleucine (L- a lle 1 ) and L- Pro 9 residues in the linear nonapeptide at the final step of the synthesis. Synthesized aureobasidin A was completely identical with the natural antibiotic with respect to antifungal activity and physicochemical properties. Unusual reactions due to N -methylamino acid, an oxazoline-mediated reaction and an N , O -acyl migration, are also described.

Site-specific ring opening of depsipeptide aureobasidin A in hydrogen fluoride

Abstract A site-specific ring opening reaction for the antifungal depsipeptide aureobasidin A occurred on treatment with HF at room temperature for 1 hour. The open-chain peptide thus obtained was recyclized to afford the original aureobasidin A without any modification.

Candida Albicans Aspartic Proteinase: cDNA Cloning and Comparison among Strains

The increasing incidence of fungal infections in immunocompromised individuals has focused attention on the importance of Candida species, particularly Candida albicans as the major opportunistic fungal pathogen. Among several putative virulence factors of C albicans SAP (secreted aspartic proteinase) produced and excreted by this yeast has been considered primarily responsible for its pathogenicity. Although this possibility is supported by experimental data reported from several different laboratories, the actual pathogenetic role of C albicans aspartic proteinase in the development of candidiasis remains unclear. In the course of studies which were attempted to answer this question, we initially undertook the cDNA cloning of this enzyme.

Conformational feature of aureobasidin E, a new type of potent antifungal antibiotic

The crystal structure of aureobasidin E, a new type of potent antifungal antibiotic, revealed the molecular conformation stably held by three intramolecular NH ⋯ OC hydrogen bonds, showing a possible feature responsible for its biological activity.