Functional promoter elements common to ribosomal protein and ribosomal RNA genes in Neurospora crassa

The promoter sequences of a cytoplasmic ribosomal protein gene (crp-2) of Neurospora crassa were identified using promoter deletion and substitution mutants. A gene-targeting strategy was used to assay the mutants in vivo. The promoter architecture of crp-2 is complex and is more similar to that of ribosomal protein genes in mouse than in Saccharomyces cerevisiae. Six regions were identified as important for transcription. These included two elements, a CG repeat and a Dde box, that are conserved in most other promoters of N. crassa ribosomal protein genes and have also been demonstrated as being required for transcription from the 40 S rRNA promoter by RNA polymerase I in vitro. The CG repeats located at -73 to -66 and between -189 and -154 were functionally redundant and increased transcription efficiency by 10- to 15- fold. The Dde boxes located at -153 to -147 and at -95 to -83 contributed 2-fold and 5-fold to transcription efficiency, respectively. An unidentified element between -254 and -190 contributed 2-fold, while a pyrimidine-rich region between -85 and -66 influenced the start point of transcription.