期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1990
卷号：87
期号：19
页码：7628-7632
DOI：10.1073/pnas.87.19.7628
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Circular RNA replicons have been reported in plants and, in one case, in animal cells. We describe such an element in yeast. In certain yeast strains, a 20S RNA species appears on transfer of cells to acetate medium. This phenotype shows cytoplasmic (non-Mendelian) inheritance and the 20S RNA is associated with 23-kDa protein subunits as a 32S particle. We demonstrate that yeast 20S RNA is an independent replicon with no homology to host genomic, mitochondrial, or 2-microns plasmid DNA or to the L-A, L-BC, or M1 double-stranded RNA viruses of yeast. The circularity of the 20S RNA is shown by the apparent absence of 3' and 5' ends, by two-dimensional gel electrophoresis, and by electron microscopy. Replication of yeast 20S RNA proceeds through an RNA-RNA pathway, and a 10,000-fold amplification occurs on shift to acetate medium. The copy number of 20S RNA is also reduced severalfold by the SKI gene products, a host antiviral system that also lowers the copy numbers of yeast double-stranded RNA viruses. Yeast 20S RNA and the hepatitis delta virus show some similarities.
