Cosson Bertrand, Gautier-Courteille Carole, Maniey Dominique, Aït-Ahmed Ounissa, Lesimple Michelle, Osborne H Beverley, Paillard Luc
CNRS UMR 6061, IFR 140, Université de Rennes 1, Faculté de Médecine, 2 Avenue Léon Bernard, 35043 Rennes Cedex, France.
Biol Cell. 2006 Nov;98(11):653-65. doi: 10.1042/BC20060054.
mRNA deadenylation [shortening of the poly(A) tail] is often triggered by specific sequence elements present within mRNA 3' untranslated regions and generally causes rapid degradation of the mRNA. In vertebrates, many of these deadenylation elements are called AREs (AU-rich elements). The EDEN (embryo deadenylation element) sequence is a Xenopus class III ARE. EDEN acts by binding a specific factor, EDEN-BP (EDEN-binding protein), which in turn stimulates deadenylation.
We show here that EDEN-BP is able to oligomerize. A 27-amino-acid region of EDEN-BP was identified as a key domain for oligomerization. A mutant of EDEN-BP lacking this region was unable to oligomerize, and a peptide corresponding to this region competitively inhibited the oligomerization of full-length EDEN-BP. Impairing oligomerization by either of these two methods specifically abolished EDEN-dependent deadenylation. Furthermore, impairing oligomerization inhibited the binding of EDEN-BP to its target RNA, demonstrating a strong coupling between EDEN-BP oligomerization and RNA binding.
These data, showing that the oligomerization of EDEN-BP is required for binding of the protein on its target RNA and for EDEN-dependent deadenylation in Xenopus embryos, will be important for the identification of cofactors required for the deadenylation process.
mRNA去腺苷酸化（多聚腺苷酸尾的缩短）通常由mRNA 3'非翻译区内存在的特定序列元件触发，一般会导致mRNA迅速降解。在脊椎动物中，许多这类去腺苷酸化元件被称为富含AU元件（AREs）。胚胎去腺苷酸化元件（EDEN）序列是非洲爪蟾III类富含AU元件。EDEN通过结合一种特定因子——EDEN结合蛋白（EDEN-BP）发挥作用，而EDEN-BP反过来会刺激去腺苷酸化。
我们在此表明EDEN-BP能够发生寡聚化。EDEN-BP的一个27个氨基酸的区域被确定为寡聚化的关键结构域。缺乏该区域的EDEN-BP突变体无法寡聚化，并且与该区域对应的肽竞争性抑制全长EDEN-BP的寡聚化。通过这两种方法中的任何一种损害寡聚化都会特异性地消除依赖于EDEN的去腺苷酸化。此外，损害寡聚化会抑制EDEN-BP与其靶RNA的结合，这表明EDEN-BP寡聚化与RNA结合之间存在紧密联系。
这些数据表明，EDEN-BP的寡聚化对于该蛋白在非洲爪蟾胚胎中与其靶RNA的结合以及依赖于EDEN的去腺苷酸化是必需的，这对于鉴定去腺苷酸化过程所需的辅助因子将具有重要意义。
