Department of Biochemistry, Dalhousie University, Halifax, Nova Scotia, Canada.
In the mtDNA of Chlamydomonas reinhardtii, a unicellular green alga, we have identified a set of short repeated sequences up to 65 nucleotides long, each of which contains the palindromic consensus motif CTCGG(N4-14)CCGAG. Most of these repeated elements are localized in spacer regions that flank the transcribed coding regions of C. reinhardtii mtDNA. These algal mitochondrial repeats have features reminiscent of short repeats in some fungal mtDNAs, such as GC clusters in Saccharomyces cerevisiae and PstI palindromes in Neurospora crassa. The location of these elements suggests that they could play a role in gene expression, e.g., post-transcriptional processing, in C. reinhardtii mitochondria.