title: An intronic open reading frame was released from one of group II introns in the mitochondrial genome of the haptophyteChrysochromulinasp. NIES-1333.
abstract: Mitochondrial (mt) genome sequences, which often bear introns, have been sampled from phylogenetically diverse eukaryotes. Thus, we can anticipate novel insights into intron evolution from previously unstudied mt genomes. We here investigated the origins and evolution of three introns in the mt genome of the haptophyteChrysochromulinasp. NIES-1333, which was sequenced completely in this study. All the three introns were characterized as group II, on the basis of predicted secondary structure, and the conserved sequence motifs at the 5' and 3' termini. Our comparative studies on diverse mt genomes prompt us to propose that theChrysochromulinamt genome laterally acquired the introns from mt genomes in distantly related eukaryotes. Many group II introns harbor intronic open reading frames for the proteins (intron-encoded proteins or IEPs), which likely facilitate the splicing of their host introns. However, we propose that a "free-standing," IEP-like protein, which is not encoded within any introns in theChrysochromulinamt genome, is involved in the splicing of the firstcox1intron that lacks any open reading frames.
authors: Graduate School of Life and Environmental Sciences; University of Tsukuba; Tsukuba, Japan ; Graduate School of Systems and Information Engineering; University of Tsukuba; Tsukuba, Japan.
authors: Yuki
authors: Y
authors: Nishimura
authors: Graduate School of Human and Environmental Studies; Kyoto University; Kyoto, Japan ; Graduate School of Global Environmental Studies; Kyoto University; Kyoto, Japan.
authors: Ryoma
authors: R
authors: Kamikawa
authors: Graduate School of Life and Environmental Sciences; University of Tsukuba; Tsukuba, Japan ; Center for Computational Sciences; University of Tsukuba; Tsukuba, Japan.
authors: Tetsuo
authors: T
authors: Hashimoto
authors: Graduate School of Life and Environmental Sciences; University of Tsukuba; Tsukuba, Japan ; Center for Computational Sciences; University of Tsukuba; Tsukuba, Japan.
authors: Yuji
authors: Y
authors: Inagaki
keywords: Chrysochromulina sp; group II intron; intron encoded protein; lateral intron transfer; mitochondrial genome