Direct binding of yeast transcription factor (TFIID) to the ribosomal protein L32 (rpL32) TATA-less promoter sequence.

The ribosomal protein L32 (rpL32) gene transcribed by RNA polymerase II lacks a canonical TATA element, that binds the transcription factor TFIID tau or TBP (TATA binding protein). Instead this promoter contains an element, termed gamma, located at -30 relative to the transcription initiation site. We previously reported that, despite the lack of a canonical TATA element the rpL32 gene utilizes yeast TFIID tau for its transcriptional initiation. Whether TFIID tau participates in rpL32 gene transcription by binding directly to a promoter element or through another protein has not been resolved. These studies reveal that proteins ranging in size from 20-40 kDa binds to the gamma-element. The 40 kDa protein(s) displays strong affinity for the canonical TATA element and may be related or equivalent to TFIID tau. Furthermore, cloned and purified yeast TFIID (TBP) binds directly to the gamma-element implying that the gamma-element directs RNA polymerase II-dependent transcription of the rpL32 gene.