Abstract
The green alga Scenedesmus pupukensis and the red alga Porphyra spiralis contain large group-IC1 introns in their nuclear small subunit ribosomal RNA genes due to the presence of open reading frames at the 5′ end of the introns. The putative 555 amino-acid Scenedesmus-encoded protein harbors a sequence motif resembling the bacterial S9 ribosomal proteins. The Porphyra intron self-splices in vitro, and generates both ligated exons and a full-length intron RNA circle. The Porphyra intron has an unusual structural organization by encoding a potential 149 amino-acid homing-endonuclease-like protein on the complementary strand. A comparison between related group-I introns in the Bangiophyceae revealed homing-endonuclease-like pseudogenes due to frame-shifts and deletions in Porphyra and Bangia. The Scenedesmus and Porphyra introns provide new insights into the evolution and possible novel functions of nuclear group-I intron proteins.
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Received: 26 May / 25 August 1999
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Haugen, P., Huss, V., Nielsen, H. et al. Complex group-I introns in nuclear SSU rDNA of red and green algae: evidence of homing-endonuclease pseudogenes in the Bangiophyceae. Curr Genet 36, 345–353 (1999). https://doi.org/10.1007/s002940050509
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DOI: https://doi.org/10.1007/s002940050509