Roles of a Trypanosoma brucei 5′→3′ exoribonuclease homolog in mRNA degradation
Roles of a Trypanosoma brucei 5′→3′ exoribonuclease homolog in mRNA degradation
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DOI：
10.1261/rna.291506
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发表时间：
2006-12-01
期刊：
影响因子：
4.5
通讯作者：
Clayton, Christine
中科院分区：
文献类型：
--
作者：
Li, Chi-Ho;Irmer, Henriette;Clayton, Christine
动质体寄生虫布氏锥虫的基因组编码酿酒酵母 5'->3' 核糖核酸外切酶 Xrn1p 和 Xrn2p/Rat1p、XRNA、XRNB、XRNC 和 XRND 的四种同源物。在酿酒酵母中，Xrn1p 是一种参与 mRNA 降解的胞质酶，而 Xrn2p 参与细胞核中的 RNA 加工。锥虫 XRND 存在于细胞核中，XRNB 和 XRNC 存在于细胞质中，XRNA 似乎存在于两个区室中。 XRND 和 XRNA 对于寄生虫的生长至关重要。 XRNA 的耗尽增加了高度不稳定的发育调节 mRNA 的丰度，这可能是通过延迟不依赖于去腺苷化的衰变途径来实现的。尽管观察到平均 Poly(A) 尾长略有下降，但更稳定或不受调节的 mRNA 的降解不受 XRNA 消耗的影响。我们得出的结论是，在锥虫中，5'-> 3' 核酸外切酶活性对于高度不稳定、受调节的 mRNA 的降解非常重要，但对于其他 mRNA，另一个步骤在确定降解速率方面更为重要。
The genome of the kinetoplastid parasite Trypanosoma brucei encodes four homologs of the Saccharomyces cerevisiae 5'-> 3' exoribonucleases Xrn1p and Xrn2p/Rat1p, XRNA, XRNB, XRNC, and XRND. In S. cerevisiae, Xrn1p is a cytosolic enzyme involved in degradation of mRNA, whereas Xrn2p is involved in RNA processing in the nucleus. Trypanosome XRND was found in the nucleus, XRNB and XRNC were found in the cytoplasm, and XRNA appeared to be in both compartments. XRND and XRNA were essential for parasite growth. Depletion of XRNA increased the abundances of highly unstable developmentally regulated mRNAs, perhaps by delaying a deadenylation-independent decay pathway. Degradation of more stable or unregulated mRNAs was not affected by XRNA depletion although a slight decrease in average poly(A) tail length was observed. We conclude that in trypanosomes 5'-> 3' exonuclease activity is important in degradation of highly unstable, regulated mRNAs, but that for other mRNAs another step is more important in determining the decay rate.