NUCLEOTIDE-SEQUENCE AND CHARACTERIZATION OF THE LARGE MITOCHONDRIAL RIBOSOMAL-RNA GENE OF PENICILLIUM-URTICAE, AND ITS COMPARISON WITH THOSE OF OTHER FILAMENTOUS FUNGI

The nucleotide sequence of a large rRNA gene and its flanking regions in cloned fragments of mitochondrial DNA from a patulin producer, Peni cillium urticae NRRL2159A, was determined by dideoxy sequencing, and t he 5' end and intron-exon border of the 1-rRNA gene were determined by primer extension analysis and RNA sequencing, respectively. In additi on to the extensive sequence homology of the 3' end of the P. urticae mt 1-rRNA gene with those of Aspergillus nidulans and Neurospora crass a, the P. urticae gene had a 1,685 bp intron which separates a 3,307 b p 5' exon and a 583 bp 3' exon. In spite of being closely related Peni cillium species, the size of the 5' exon of the P. urticae mt 1-rRNA i s 472 bp larger than that of P. chrysogenum, whereas the sizes of the 3' exon and intron of P. urticae are very similar to those of P. chrys ogenum (581 bp for the 3' exon and 1,678 bp for the intron). The intro n of P. urticae contains a structure similar to the consensus one of t he self splicing group IA intron and a large open reading frame sugges ted to be a gene for ribosomal protein S5. A sequence similar to the I -SceI recognition sequence was found at the exon-intron border. Extens ive sequence homology was observed between P. urticae and P. chrysogen um, exceptions being in four regions in the 5' exon. These non-homolog ous regions were located in the hairpin and variable regions outside o f the core structures. Comparison of the mt 1-rRNA sequences of severa l filamentous fungi revealed that the above four non-homologous region s are greatly expanded, and two other non-homologous regions appear at the 3' ends of the 5' exon and 3' exon.