Search

Abstract: Lignocellulose, the major reservoir of organic carbon on Earth, is recalcitrant to turnover and resistant to microbial and enzymatic attack because of the protective action of lignin and the crystalline structure of cellulose. Basidiomycetes are the only organisms known to degrade lignocellulose using two alternative degradation strategies: white rot basidiomycetes break down the lignin moiety extensively before attacking the cellulose, whereas brown rot basidiomycetes cause limited lignin alteration while primarily degrading cellulose. These strategies depend on complex portfolios of extracellular enzymes whose production and export are environment and substrate dependent. More than 265 fungal genomes (more than 90 corresponding to basidiomycetes) have been sequenced. These sequences can be bioinformatically screened to identify presumptive secreted proteins that, however, differ from the experimental data, stressing the importance of using complementary approaches for analyzing these complex systems. The study of fungal secretomes from the scope of their different lignin degradation strategies and lifestyles would facilitate their use in the treatment of lignocellulose as carbon feedstock for biofuel production and further biorefinery processes. In this article, we carry out a comparative review of the analytical tools and strategies used for studying basidiomycetes' secretomes and compare the available results from these two points of view. Biological significance: In this article, we review the tools and strategies used in the analysis of basidiomycetes' secretomes and we compare the secretome data available for this type of fungi with a special emphasis on the enzymes involved in lignocellulose degradation. This comparative study provides a basis for distinguishing different lifestyles (saprotrophs, symbionts and parasites) on the basis of their respective secretomes. [Copyright &y& Elsevier]

Secretome represents a main target for understanding the mechanisms of fungal adaptation. In the present study, we focus on the secretomes of fungi associated with infections in humans and other mammals in order to explore relationships between the diverse morphological and phylogenetic groups. Almost all the mammalian pathogenic fungi analyzed have secretome sizes smaller than 1000 proteins and, secreted proteins comprise between 5% and 10% of the total proteome. As expected, the correlation pattern between the secretome size and the total proteome was similar to that described in previous secretome studies of fungi. With regard to the morphological groups, minimum secretome sizes of less than 250 secreted proteins and low values for the fraction of secreted proteins are shown in mammalian pathogenic fungi with reduced proteomes such as microsporidia, atypical fungi and some species of yeasts and yeast-like fungi (Malassezia). On the other hand, filamentous fungi have significantly more secreted proteins and the highest numbers are present in species of filamentous fungi that also are plant or insect pathogens (Fusarium verticilloides , Fusarium oxysporum and Basidiobolus meristosporus). With respect to phylogeny, there are also variations in secretome size across fungal subphyla: Microsporidia , Taphrinomycotina , Ustilagomycotina and Saccharomycotina contain small secretomes; whereas larger secretomes are found in Agaricomycotina , Pezizomycotina , Mucoromycotina and Entomophthoromycotina. Finally, principal component analysis (PCA) was conducted on the complete secretomes. The PCA results revealed that, in general, secretomes of fungi belonging to the same morphological group or subphyla cluster together. In conclusion, our results point out that in medically important fungi there is a relationship between the secretome and the morphological group or phylogenetic classification. • Secretomes of fungi infecting humans and other mammals were bioinformatically predicted. • The majority of species contained secretomes with less than 1000 proteins. • Secretome size correlated with the total proteome. • Complete secretomes were subjected to principal component analysis (PCA). • Secretome was related to the morphological group and/or phylogenetic classification. [ABSTRACT FROM AUTHOR]