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首页> 外文期刊>Molecular and Cellular Biology >Nop2p is required for pre-rRNA processing and 60S ribosome subunit synthesis in yeast.
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Nop2p is required for pre-rRNA processing and 60S ribosome subunit synthesis in yeast.

机译：在酵母中进行rRNA前加工和60S核糖体亚基合成需要Nop2p。

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To investigate the function of the nucleolar protein Nop2p in Saccharomyces cerevisiae, we constructed a strain in which NOP2 is under the control of a repressible promoter. Repression of NOP2 expression lengthens the doubling time of this strain about fivefold and reduces steady-state levels of 60S ribosomal subunits, 80S ribosomes, and polysomes. Levels of 40S subunits increase as the free pool of 60S subunits is reduced. Nop2p depletion impairs processing of the 35S pre-rRNA and inhibits processing of 27S pre-rRNA, which results in lower steady-state levels of 25S rRNA and 5.8S rRNA. Processing of 20S pre-rRNA to 18S rRNA is not significantly affected. Processing at sites A2, A3, B1L, and B1S and the generation of 5' termini of different pre-rRNA intermediates appear to be normal after Nop2p depletion. Sequence comparisons suggest that Nop2p may function as a methyltransferase. 2'-O-ribose methylation of the conserved site UmGm psi UC2922 is known to take place during processing of 27S pre-rRNA. Although Nop2p depletion lengthens the half-life of 27S pre-RNA, methylation of UmGm psi UC2922 in 27S pre-rRNA is low during Nop2p depletion. However, methylation of UmGm psi UC2922 in mature 25S rRNA appears normal. These findings provide evidence for a close interconnection between methylation at this conserved site and the processing step that yields the 25S rRNA.
机译：为了研究核糖蛋白Nop2p在酿酒酵母中的功能，我们构建了其中NOP2在可抑制启动子控制下的菌株。抑制NOP2表达可使该菌株的倍增时间延长约五倍，并降低60S核糖体亚基，80S核糖体和多核糖体的稳态水平。随着60S亚基的自由池减少，40S亚基的水平增加。 Nop2p耗竭会损害35S pre-rRNA的加工并抑制27S pre-rRNA的加工，从而导致较低的25S rRNA和5.8S rRNA稳态水平。从20S pre-rRNA到18S rRNA的加工不会受到明显影响。在Nop2p耗尽后，在位点A2，A3，B1L和B1S的加工以及不同的pre-rRNA中间体的5'末端的生成似乎是正常的。序列比较表明Nop2p可能起甲基转移酶的作用。已知保守位点UmGm psi UC2922的2'-O-核糖甲基化发生在27S pre-rRNA加工过程中。尽管Nop2p耗竭延长了27S pre-RNA的半衰期，但在Nop2p耗竭期间，UmGm psi UC2922在27S pre-rRNA中的甲基化水平很低。但是，成熟的25S rRNA中UmGm psi UC2922的甲基化似乎是正常的。这些发现为该保守位点的甲基化与产生25S rRNA的加工步骤之间的紧密联系提供了证据。

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