Nucleic Acids Research, 1990, Vol. 18, No. 7 1805-1811
© 1990
MOLECULAR BIOLOGY |
Two complex regions, including a TATA sequence, are required for transcription by RNA polymerase I in Neurospora crassa
Department of Plant Pathology, University of California at Davis Davis, CA 95616, USA
Received November 27, 1989. Revised March 5, 1990. Accepted March 5, 1990.
In order to define the RNA polymerase I transcriptional apparatus and how it might interact with regulatory signals, the DNA sequences necessary for 40S rRNA transcription in Neurospora crassa were determined. A systematic set of deletion, substitution and insertion mutations were assayed in a homologous in vitro system. The sequences required for transcription of the gene consist of two large domains (I and II) from –113 to –37, and –29 to +4, respectively. Complete deletion of either domain abolished transcription. Upstream sequences confer a small stimulation of transcription. Domain II includes a TATA sequence at –5 which is sensitive to a small (2 bp) substitution and which is conserved among the large rRNA genes of many organisms. Domain I Includes a sequence, termed the ‘Ribo box’, which is also required for transcription of the Neurospora, 5S rRNA genes (1), and which occurs in the 5' region of a Neurospora ribosomal protein gene. The 5S and 40S Ribo boxes are shown to be functionally interchangeable.