Dechampesme A M, Koroleva O, Leger-Silvestre I, Gas N, Camier S
Service de Biochimie et de Génétique Moléculaire, Commissariat á L'Energie Atomique (CEA)/Saclay, F-91191 Gif-sur-Yvette Cedex, France.
J Cell Biol. 1999 Jun 28;145(7):1369-80. doi: 10.1083/jcb.145.7.1369.
A collection of yeast strains surviving with mutant 5S RNA has been constructed. The mutant strains presented alterations of the nucleolar structure, with less granular component, and a delocalization of the 25S rRNA throughout the nucleoplasm. The 5S RNA mutations affected helix I and resulted in decreased amounts of stable 5S RNA and of the ribosomal 60S subunits. The shortage of 60S subunits was due to a specific defect in the processing of the 27SB precursor RNA that gives rise to the mature 25S and 5.8S rRNA. The processing rate of the 27SB pre-rRNA was specifically delayed, whereas the 27SA and 20S pre-rRNA were processed at a normal rate. The defect was partially corrected by increasing the amount of mutant 5S RNA. We propose that the 5S RNA is recruited by the pre-60S particle and that its recruitment is necessary for the efficient processing of the 27SB RNA precursor. Such a mechanism could ensure that all newly formed mature 60S subunits contain stoichiometric amounts of the three rRNA components.
已构建了一组携带突变型5S RNA存活的酵母菌株。这些突变菌株呈现核仁结构改变，颗粒成分减少，且25S rRNA在整个核质中发生移位。5S RNA突变影响螺旋I，导致稳定的5S RNA和核糖体60S亚基数量减少。60S亚基的短缺是由于产生成熟25S和5.8S rRNA的27SB前体RNA加工过程中存在特定缺陷。27SB前体rRNA的加工速率被特异性延迟，而27SA和20S前体rRNA以正常速率加工。通过增加突变型5S RNA的量，该缺陷得到部分纠正。我们提出5S RNA被60S前体颗粒招募，且其招募对于27SB RNA前体的有效加工是必要的。这样一种机制可确保所有新形成的成熟60S亚基包含化学计量的三种rRNA成分。
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