The early diverging ascomycetous budding yeast Saitoella complicata has three histone deacetylases belonging to the Clr6, Hos2, and Rpd3 lineages

Abstract

We sequenced the genomic DNA and the transcribed RNA of the ascomycetous budding yeast Saitoella complicata, which belongs to the earliest lineage (Taphrinomycotina) of ascomycetes. We found 3 protein-coding regions similar to Clr6 of Schizosaccharomyces (a member of Taphrinomycotina). Clr6 has a structure similar to that of Rpd3 and Hos2 of Saccharomyces. These proteins belong to the class 1 histone deacetylase (HDAC) family. The phylogenetic tree showed that the Clr6, Hos2, and Rpd3 lineages are separated in fungal HDACs. Basidiomycetes have 3 proteins belonging to the Clr6, Hos2, and Rpd3 lineages. On the other hand, whereas ascomycetes except for Schizosaccharomyces have the Hos2 and Rpd3 homologs, and lack the Clr6 homolog, Schizosaccharomyces has the Clr6 and Hos2 homologs, and lacks the Rpd3 homolog. Interestingly, Pneumocystis and Saitoella have 3 proteins belonging to the Clr6, Hos2, and Rpd3 lineages. Thus, these fungi are the first ascomycete found to possess all 3 types. Our findings indicated that Taphrinomycotina has conserved the Clr6 protein, suggesting that the ancestor of Dikarya (ascomycetes and basidiomycetes) had 3 proteins belonging to the Clr6, Hos2, and Rpd3 lineages. During ascomycete evolution, Pezizomycotina and Saccharomycotina appear to have lost their Clr6 homologs and Schizosaccharomyces to have lost its Rpd3 homolog.Key words: ascomycetes; basidiomycetes; histone deacetylase; Saitoella complicata; Schizosaccharomyces IntroductionThe subphylum Taphrinomycotina ( Archiascomycetes ) is the earliest ascomycetous lineage that diverged before the separation of the subphyla Pezizomycotina ( Euascomycetes ) and Saccharomycotina ( Hemiascomycetes ) (Nishida and Sugiyama, 1993;An et al., 2002;Liu et al., 2009;Schoch et al., 2009). Genome analyses of ascomycetes belonging to Taphrinomycotina are central to the elucidation of ascomycetes evolution. At present, genome information on Taphrinomycotina is limited to that of species belonging to the genus Schizosaccharomyces (Wood et al., 2002;Rhind et al., 2011). The anamorphic and saprobic yeast Saitoella complicata is a member of Taphrinomycotina which has been isolated from Himalayan soil . Although Schizosaccharomyces is a fission yeast, Saitoella is a budding yeast. Saitoella complicata shares some characteristics with both ascomycetous and basidiomycetous yeasts (Sugiyama et al., 1985;Goto et al., 1987). For example, a negative diazonium blue B reaction and negative extracellular deoxyribonuclease activity are characteristics of ascomycetous yeasts, whereas positive urease activity, the major ubiquinone system Q-10, and enteroblastic budding are traits of basidiomycetous yeasts (Sugiyama et al., 1985;Goto et al., 1987). Based on 18S ribosomal DNA sequence comparison, Saitoella complicata forms a monophyletic lineage with Schizosaccharomyces pombe and Taphrina Full PaperThe early diverging ascomycetous budding yeast Saitoella complicata has three histone deacetylases belonging to the Clr6, Hos2, and Rpd3 lineages (Received July 17, 2013; Acc...

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