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

Abstract

The ribosomal protein L32 (rpL32) gene transcribed by RNA polymerase II lacks a canonical TATA element, that binds the transcription factor TFIID τ or TBP (TATA binding protein). Instead this promoter contains an element, termed γ, 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 τ for its transcriptional initiation. Whether TFIID τ 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 γ-element. The 40 kDa protein(s) displays strong affinity for the canonical TATA element and may be related or equivalent to TFIID τ. Furthermore, cloned and purified yeast TFIID (TBP) binds directly to the γ-element implying that the γ-element directs RNA polymerase II-dependent transcription of the rpL32 gene.