Structure of a Neurospora RNA polymerase I promoter defined by transcription in vitro with homologous extracts. Nucleic Acids. Res

A Neurospora in vitro transcription system has been developed which specifically and eTFiciently initiates transcription of a cloned Neurospora crassa ribosomal RNA gene by KMA polymerase 1. The initiation site of transcription (both in vitro and in vivo) appears to be located about 850 bp from the 5 ' end of nature 17S rRHA. However, the primary rRhA transcripts are normally cleaved very rapidly at a site 120-125 nt from the 5 ' end in vitro and in vivo. The nucleotide sequence surrounding the initiation site has been determined. The region from-16 to +9 exhibits partial homology to the corresponding sequences from a wide variety of organisms including yeast, but the most striking similarity is to the initiation region from Dictyostellun discoldeum which displays 73Z homology to the Neurospora sequence from-23 to +47. The Neurospora sequences from-96 to +97 have been shown to be sufficient for transcription. This region contains two sequences displaying 8/9 bp matches to elements of the 5S rDNA promoter