Analysis of differentially expressed genes associated with tryptophan-dependent pigment synthesis inM. furfurby cDNA subtraction technology

Abstract

Malassezia species are associated with pityriasis versicolor (PV) and its depigmented variant pityriasis versicolor alba (PVa), widespread fungal skin infections in humans. The pathogenesis of PV and PVa remains unclear, including their clinical and histological symptoms such as hyper- and depigmentation, reduced responsiveness to ultraviolet radiation and lack of inflammatory reaction despite high fungal load. Pigments produced by M. furfur are possibly involved in the pathogenesis of PV. In vitro, M. furfur produces a wide range of pigments and fluorochromes when cultured with tryptophan as the sole nitrogen source. We have begun to analyse the molecular basis of pigment production by searching for genes associated with tryptophan-based pigment production. A suppression subtractive hybridization (SSH) protocol was used to identify genes expressed in M. furfur cells producing pigments, but not in non-induced cells. SSH was performed 3 and 5 h after onset of pigment induction. Up-regulation of genes in the pigment-producing cells was confirmed by reverse northern analysis. More than 1,500 cDNA sequences of both the indicated time points were analysed. We identified a wide variety of genes associated with metabolism and several genes with unknown function are specifically expressed during pigment production. Furthermore, a fraction of genes possibly involved in different steps of the newly discovered indolic pathway of M. furfur were expressed in pigment producing cells. These data provide the first molecular insight into pigment production of M. furfur.

Candida glabrata tryptophan‐based pigment production via the Ehrlich pathway

“…, 1998; Mayser et al. , 2007), the biochemical pathway of tryptophan‐induced pigment production, the genes involved in the biosynthesis of this pigment by human pathogenic fungi in general and the biological roles of pigmentation for C. glabrata in particular have remained elusive (Hort et al. , 2008).…”

“…Very little is known about the genetic basis of M. furfur pigment synthesis, mainly due to the lack of molecular tools for this fungus (Hort et al. , 2008).…”

Differentially expressed genes associated with tryptophan-dependent pigment synthesis in Malassezia furfur- a comparison with the recently published genome of Malassezia globosa

“…As described by Hort et al. [13], the final PCR products obtained by SSH were cloned in E. coli using the pCR II‐Topo‐Vector (Invitrogen) and screened for differential expression via reverse Northern blot according to standard protocols 16 . Differentially expressed genes were sequenced using the BigDye Cycle Sequencing Kit (Applied Biosystems, Foster City, CA, USA).…”

“…The classification by dedicated functions performed by Hort et al. [13] according to the yeast functional catalogue (http://mips.gsf.de/proj/funcatDB/search_main_frame.html) remained unchanged. Matches showing an expect value above 1e‐3 were placed into the category ‘no significant similarity’.…”

Fungi on the Skin: Dermatophytes and Malassezia

“…Genomics may not readily provide insight into the pathways of indole production, as many indoles can be formed from tryptophan and indole pyruvic acid in the absence of cells, suggesting that a trypto- phan aminotransferase may be the only enzyme necessary for the synthesis of these indoles (Zuther et al 2008). However, additional enzymes may be used in vivo, and Hort et al (2009) have identified some candidate M. furfur genes with a role in indole synthesis.…”