| (1) | Department of Microbiology, La Trobe University, Bundoora 3083, Melbourne, Australia |
| (2) | Department of Anatomy and Cell Biology, University of Melbourne, Parkville, Melbourne, Australia |
| (3) | Institute of Biological Sciences, University of Tsukuba, Ibaraki 305-8572, Japan |
| (4) | Division of Biological Sciences, University of Missouri, Columbia, MO 65211-7400, USA |
Abstract. The circular mitochondrial genome of Dictyostelium discoideum has a size of 55,564 base pairs. We present here a complete and detailed transcription map of the mitochondrial DNA. Eight major, polycistronic transcripts encoding polypeptides, ribosomal RNAs and interspersed transfer RNAs were identified in Northern hybridization studies. Most of these polycistronic transcripts are subsequently processed into smaller mono-, di- or tricistronic RNAs. In some cases, the maturation involves endonucleolytic cleavage of the transcripts using transfer RNAs as excision signals. Primer extension experiments mapped the 5' ends of the transcripts, which may represent transcription initiation sites. Two of the polycistronic transcripts were found to be overlapping. Based on sequence alignments of the potential transcription start sites, a short oligonucleotide consensus initiation sequence has been identified which does not reveal any significant sequence homologies to known promoter regions from other organisms.
Keywords. Mitochondrial genome - Co-transcription - Polycistronic
- Transcription initiation
| E-mail: fisher@lumi.latrobe.edu.au |