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Polyadenylation of rRNA in Saccharomyces cerevisiae
Letian Kuai, Feng Fang, J. Scott Butler and Fred Sherman
Proceedings of the National Academy of Sciences of the United States of America
Vol. 101, No. 23 (Jun. 8, 2004), pp. 8581-8586
Published by: National Academy of Sciences
Stable URL: http://www.jstor.org/stable/3372300
Page Count: 6
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In contrast to mRNAs, rRNAs are transcribed by RNA polymerase I or III and are not believed to be polyadenylated. Here we show that in Saccharomyces cerevisiae, at least a small fraction of rRNAs do have a poly(A) tail. The levels of polyadenylated rRNAs are dramatically increased in strains lacking the degradation function of Rrp6p, a component of the nuclear exosome. Pap1p, the poly(A) polymerase, is responsible for adenylating the rRNAs despite the fact that the rRNAs do not have a canonical polyadenylation signal. Polyadenylated rRNAs reside mainly within the nucleus and are in turn degraded. For at least one rRNA type, the polyadenylation preferentially occurs on the precursor rather than the mature product. The existence of polyadenylated rRNAs may reflect a quality-control mechanism of rRNA biogenesis.
Proceedings of the National Academy of Sciences of the United States of America © 2004 National Academy of Sciences