Fungi in the genus Malassezia are ubiquitous skin residents of humans and other warm-blooded animals. Malassezia are involved in disorders including dandruff and seborrheic dermatitis, which together affect >50% of humans. Despite the importance of Malassezia in common skin diseases, remarkably little is known at the molecular level. We describe the genome, secretory proteome, and expression of selected genes of Malassezia globosa. Further, we report a comparative survey of the genome and secretory proteome of Malassezia restricta, a close relative implicated in similar skin disorders. Adaptation to the skin environment and associated pathogenicity may be due to unique metabolic limitations and capabilities. For example, the lipid dependence of M. globosa can be explained by the apparent absence of a fatty acid synthase gene. The inability to synthesize fatty acids may be complemented by the presence of multiple secreted lipases to aid in harvesting host lipids. In addition, an abundance of genes encoding secreted hydrolases (e.g., lipases, phospholipases, aspartyl proteases, and acid sphingomyelinases) was found in the M. globosa genome. In contrast, the phylogenetically closely related plant pathogen Ustilago maydis encodes a different arsenal of extracellular hydrolases with more copies of glycosyl hydrolase genes. M. globosa shares a similar arsenal of extracellular hydrolases with the phylogenetically distant human pathogen, Candida albicans, which occupies a similar niche, indicating the importance of host-specific adaptation. The M. globosa genome sequence also revealed the presence of mating-type genes, providing an indication that Malassezia may be capable of sex.fungal genomics ͉ fungal proteomics ͉ seborrheic dermatitis ͉ skin ͉ fungal mating

A method has been developed for de novo peptide sequencing using matrix-assisted laser desorption ionization mass spectrometry. This method will facilitate biological studies that require rapid determination of peptide or protein sequences, e.g., determination of posttranslational modifications, identification of active compounds isolated from combinatorial peptide libraries, and the selective identification of proteins as part of proteome studies. The method involves fast, one-step addition of a sulfonic acid group to the N terminus of tryptic peptides followed by acquisition of postsource decay (PSD) fragment ion spectra. The derivatives are designed to promote efficient charge site-initiated fragmentation of the backbone amide bonds and to selectively enhance the detection of a single fragment ion series that contains the C terminus of the molecule (y-ions). The overall method has been applied to pmol quantities of peptides. The resulting PSD fragment ion spectra often exhibit uninterrupted sequences of 20 or more amino acid residues. However, fragmentation efficiency decreases considerably at amide bonds on the C-terminal side of Pro. The spectra are simple enough that de novo sequence tagging is routine. The technique has been successfully applied to peptide mixtures, to high-mass peptides (up to 3,600 Da) and to the unambiguous identification of proteins isolated from two-dimensional gel electrophoresis. The PSD spectra of these derivatized peptides often allow far more selective protein sequence database searches than those obtained from the spectra of native peptides.Knowledge of protein sequences is fundamentally important for understanding many physiological processes at the molecular level (1). Tandem mass spectrometry has become an increasingly essential tool for protein and peptide sequencing because of its speed, sensitivity, and applicability to complex mixtures (2). Recently, postsource decay (PSD) matrix-assisted laser desorption ionization (MALDI) mass spectrometry was developed for high-sensitivity peptide sequencing applications (3-8). Subpicomole limits of analysis were reported as a result of the high yield of fragment ions and the high ion transmission inherent with time-of-flight mass spectrometry (5). Kaufmann et al. (5) also noted several problems associated with PSD MALDI sequencing of peptides, including the complexity of the resulting fragmentation patterns and the lack of computer algorithms capable of interpreting the complex spectra. The recent incorporation of delayed extraction (DE) (9, 10), a technique designed to improve precursor-ion mass resolution and mass-measurement accuracy, reduced the rate of PSD fragmentation by at least an order of magnitude. As a result, many low-intensity precursor ions obtained by DE MALDI do not produce enough PSD fragmentation to allow derivation of even short sequence tags (7).Positively charged derivatives have been used in desorption mass spectrometry for many years to improve sensitivity by enhancing ionization efficiencies (11, 12...

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A new fast, simple, and water-compatible derivatization strategy improves protein identification.