Identification of histone H4-like TAF in Schizosaccharomyces pombe as a protein that interacts with WD repeat-containing TAF.

The general transcription factor TFIID consists of the TATA-binding protein (TBP) and multiple TBP-associated factors (TAFs). We previously identified two distinct WD repeat-containing TAFs, spTAF72 and spTAF73, in the fission yeast Schizosaccharomyces pombe. Here we report the identification of another S.pombe TAF, spTAF50, which is the S.pombe homolog of histone H4-like TAFs such as human TAF80, Drosophila TAF60 and Saccharomyces cerevisiae TAF60. spTAF50 was identified in a two-hybrid screen as a protein that interacts with the C-terminal WD repeat-containing region of spTAF72. Gene disruption revealed that spTAF50 is essential for cell viability. In vitro, spTAF50 bound to spTAF72 but less efficiently to spTAF73. In S.pombe cells, spTAF50 was detected as a protein with an apparent molecular mass of approximately 50 kDa. Immunoprecipitation experiments demonstrated that spTAF50 is present in both the TFIID and SAGA-like complexes as in the case of spTAF72. These results indicate that the C-terminal region of spTAF72, which largely consists of WD repeats, interacts with spTAF50 in the TFIID and SAGA-like complexes, suggesting a role for the WD repeat domain in the interaction between TAFs.