Glycine as a regulator of tryptophan-dependent pigment synthesis in Malassezia furfur

Abstract

The effects of the addition of different amino nitrogens on growth, morphology and secondary metabolism of Malassezia furfur were investigated. After primary culture on Dixon agar, M. furfur CBS 1878 was transferred into a fluid medium together with the nitrogen sources, glycine (Gly) or tryptophan (Trp), or a combination of both. Growth was measured by means of a direct cell counting method and pigment synthesis was photometrically assessed. Addition of glycine resulted in an exponential increase in biomass, but not in pigment production. Tryptophan as the sole nitrogen source caused distinct brown staining of the medium, without increasing biomass. Simultaneous equimolar addition of both amino acids resulted in an initial increase in biomass as a sign of preferential metabolism of glycine, followed by a growth plateau and pigment production which, caused by higher biomass, occurred more rapidly than after addition of tryptophan alone. The yeast-cell morphology changed from round to oval. Addition of glycine to the tryptophan-containing liquid culture stopped pigment formation with simultaneous growth induction. These in vitro on-off phenomena depending on the nitrogen source might be significant in the pathogenesis of pityriasis versicolor: hyperhidrosis followed by preferential consumption of individual nitrogen sources such as glycine with exponential growth and thereafter transamination of tryptophan and TRP-dependent pigment synthesis.

The Malassezia Genus in Skin and Systemic Diseases

“…The flare of disease could be associated with altered population dynamics, which would be affected not only by variations in sebaceous gland activity but also by modifications in other nutrients supplied by sweat, such as essential amino acids like glycine and tryptophan (148). It has been shown in vitro that glycine stimulates the fast growth of M. furfur, and when this amino acid is exhausted, yeast cells employ tryptophan as a nitrogen source, increasing the production of indolic metabolites (24). Such cycles of population growth, bioactive indole production, and subsequent deprivation of nutrients could result in insufficiently masked antigens and ligands on the surface of the yeast cells, which would result in the activation of the immune system.…”

New Insights into the Etiopathogenesis of Seborrheic Dermatitis

“…Glycine stimulates the fast growth of M. furfur and after its exhaustion yeast cells employ tryptophan as a nitrogen source, increasing the production of indolic metabolites [4]. Such cycles of population growth, bioactive indole production, and subsequent deprivation of nutrients result in insufficiently masked antigens and ligands on the surface of the yeast cells leading to immune system activation.…”

“…Because of smaller sebum production, seborrheic dermatitis flares occur more often in spring than in summer. Disease flare could be associated with altered population dynamics affected not only by variations in sebaceous gland activity but also by modifications in other nutrients supplied by sweat, such as essential amino acids like glycine and tryptophan.Glycine stimulates the fast growth of M. furfur and after its exhaustion yeast cells employ tryptophan as a nitrogen source, increasing the production of indolic metabolites [4]. Such cycles of population growth, bioactive indole production, and subsequent deprivation of nutrients result in insufficiently masked antigens and ligands on the surface of the yeast cells leading to immune system activation.…”

Caracterización fenotípica de aislamientos de Malassezia spp., de origen canino

“…with remaining tryptophan molecules producing pigment (17). This enzyme has been widely studied by Zuther et al (18), in the fungus Ustilago maydis.…”

“…La catalasa cuya reacción negativa permite la diferenciación de M. restricta de las demás especies del género (3,4,12). Otras pruebas que se basan en la actividad enzimática son la determinación de fosfolipasa que hidroliza enlaces éster de glicerofosfolípidos (15,16) y la triptófano aminotransferasa (TAM 1) que se encarga de transaminar el triptófano para formar indol piruvato, que reacciona espontáneamente con moléculas del triptófano restante produciendo pigmento (17). Esta última enzima ha sido ampliamente estudiada en el hongo Ustilago maydis, por Zuther et al (18), quienes demostraron que los pigmentos indólicos producidos son idénticos a los producidos por M. furfur, con lo que se puede sugerir que esta enzima podría estar involucrada en la producción del pigmento en esta especie.…”