Functional specialization of two paralogous TAF12 variants by their selective association with SAGA and TFIID transcriptional regulatory complexes

Abstract

Edited by John M. Denu TATA box-binding protein (TBP)-associated factors (TAFs), evolutionarily conserved from yeast to humans, play a central role during transcription initiation. A subset of TAF proteins is shared in transcription factor II D (TFIID) and SAGA transcription regulatory complexes. Although higher eukaryotes contain multiple TAF variants that specify tissue-and developmental stage-specific organization of TFIID or SAGA complexes, in unicellular genomes, however, each TAF is encoded by a single gene. Surprisingly, we found that the genome of Candida albicans, the predominant human fungal pathogen, contains two paralogous TAF12 genes, CaTAF12L and CaTAF12, encoding H2B-like histone-fold domain-containing variants. Of the available fungal genome sequences, only seven other closely related diploid pathogenic Candida genomes encode the two TAF12 paralogs. Using affinity purifications from C. albicans cell extracts, we demonstrate that CaTAF12L uniquely associates with the SAGA complex and CaTAF12 associates with the TFIID complex. We further show that CaTAF12, but not CaTAF12L, is essential for C. albicans growth. Conditional depletion of the two TAF12 variant proteins caused distinct cellular and colony phenotypes. Together our results define a specialized organization of the TAF12 variants and non-redundant roles for the two TAF12 variants in the unicellular C. albicans genome.

Sharing the SAGA

“…In contrast, TAF9, TAF10 and TAF12 are shared between SAGA and TFIID in most species, although there are notable exceptions to this rule. A recent study has identified two paralogs of Taf12 in the human pathogenic yeast Candida albicans , each encoding a distinct protein, Taf12 and Taf12l, which specifically associates with TFIID or SAGA, respectively [28]. Furthermore, Schizosaccharomyces pombe (sp) has two paralogous Taf5 proteins, Taf5, which is found in both SAGA and TFIID, and Taf5l, which is only found in TFIID [29].…”

Arabidopsis TBP-ASSOCIATED FACTOR 12 ortholog NOBIRO6 controls root elongation with unfolded protein response cofactor activity

“…The two Arabidopsis TAF12 proteins were recently shown to exhibit different affinities toward TFIID and SAGA components (42). The fungal pathogen Candida albicans also boasts two copies of TAF12 that participate in the growth of this unicellular organism nonredundantly, with each one showing selective interaction with the TFIID or SAGA complexes (43). Therefore, plants may also exploit multiple TAF12 isoforms for different purposes based on their interacting PIC subcomplexes, which may improve transcriptome plasticity and contribute to the strong environmental adaptability of plants.…”

Interplay between transcriptional regulators and the SAGA chromatin modifying complex fine-tune iron homeostasis

“…Details regarding construction of plasmids and C. albicans strains are available on request. Briefly, genes encoding the HAP complex subunits Hap2, Hap3, and Sef1 were genomically TAP-tagged in C. albicans strain SN152 using the plasmids Ip21 and Ip22 ( 25 ) as DNA templates and ONC645/646, ONC649/650, ONC637/638 respectively as primers and the tagging cassettes were amplified by PCR using Phusion HF DNA polymerase. Correct integration of the tagging cassettes in C. albicans strains KNC398, KNC410, and KNC379 was confirmed by PCR, and protein expression was confirmed by western blotting using rabbit polyclonal anti-TAP antibody (Thermo Fisher).…”

“…This article contains supporting information ( 11 , 13 , 14 , 19 , 25 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 ).…”

“…Acetylation of nucleosomal histone H3 at Lys9/14 is a transcriptionally active chromatin mark catalyzed by the SAGA histone acetyltransferase complex ( 22 ). SAGA is a large multifunctional protein complex that functions as a coactivator of transcription and is evolutionarily conserved from budding yeast to humans ( 23 , 24 ), and in C. albicans ( 25 ). Several key aspects of the transcriptional regulation by the HAP genes and the SEF1 gene are poorly understood.…”