Characterization of a novel small RNA encoded by Dictyostelium discoideum mitochondrial DNA |
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Authors: | M Pi T Morio H Urushihara and Y Tanaka |
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Institution: | (1) Institute of Biological Sciences, University of Tsukuba, Tsukuba, Ibaraki 305, Japan Fax: +81-298-53-6614; e-mail: ytanaka@sakura.cc.tsukuba.ac.jp, JP;(2) Center for TARA (Tsukuba Advanced Research Alliance), Institute of Biological Sciences, University of Tsukuba, Tsukuba, Ibaraki 305, Japan, JP |
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Abstract: | In this study, we analyzed a mitochondrial small (ms) RNA in Dictyostelium discoideum, which is 129 nucleotides long and has a GC content of only 22.5%. In the mitochondrial DNA, a single-copy gene (msr) for the ms RNA was located downstream of the gene for large-subunit rRNA. The location of msr was similar to that of the 5S rRNA gene in prokaryotes and chloroplasts, but clearly different from that in mitochondria
of plants, liverwort and the chlorophycean alga Prototheca wikerhamii, in which small-subunit rRNA and 5S rRNA genes are closely linked. The primary sequence of ms RNA showed low homology with
mitochondrial 5S rRNA from plants, liverwort and the chlorophycean alga, but the proposed secondary structure of ms RNA was
similar to that of cytoplasmic 5S rRNA. In addition, ms RNA showed a highly conserved GAAC sequence in the same loop as in
common 5S rRNA. However, ms RNA was detected mainly in the mitochondrial 25 000 × g supernatant fraction which was devoid of ribosomes. It is possible that ms RNA is an evolutionary derivative of mitochondrial
5S rRNA.
Received: 17 May 1997 / Accepted: 26 August 1997 |
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Keywords: | Dictyostelium discoideum Ribosome 5S rRNA Mitochondrial DNA Small RNA |
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