RNA chaperones stimulate formation and yield of the U3 snoRNA-Pre-rRNA duplexes needed for eukaryotic ribosome biogenesis.
RNA chaperones stimulate formation and yield of the U3 snoRNA-Pre-rRNA duplexes needed for eukaryotic ribosome biogenesis.
复制标题
DOI：
10.1016/j.jmb.2009.05.072
复制
发表时间：
2009-07-31
影响因子：
5.6
通讯作者：
Correll, Carl C.
中科院分区：
文献类型：
--
作者：
Gerczei, Timea;Shah, Binal N.;Manzo, Anthony J.;Walter, Nils G.;Correll, Carl C.
为了满足快速生长的真核细胞对核糖体合成的高需求，U3小核仁RNA（snoRNA）和前体核糖体RNA（pre-rRNA）之间的短双链体必须快速且高产率地形成。这些相互作用，命名为U3-ETS和U3- 18 S双链体，是启动小亚基rRNA加工所必需的。以前，我们在体外表明，对应于那些在酿酒酵母双链体后，只有观察到两种蛋白质之一：Imp3 p或Imp 4p。在这里，我们使用基于荧光和其他体外测定来确定这些蛋白质是否具有RNA伴侣活性，并评估这些活性是否足以满足体内预期的双链体产量和速率要求。这两种蛋白质与U3 snoRNA组装成伴侣复合物会使U3茎结构不稳定，显然是为了暴露其18 S碱基配对位点。因此，分子伴侣复合物将U3- 18 S双链体的形成从检测不到的速率加速到与杂交短双链体观察到的固有速率相当的速率。分子伴侣复合物还使U3-ETS双链体稳定2.7 kcal/mol。这些分子伴侣活性在宽浓度范围内提供高U3-ETS双链体产量和快速U3- 18 S双链体形成，以帮助确保U3-pre-rRNA相互作用既不限制核糖体生物合成也不限制快速细胞生长。所用的热力学和动力学框架是通用的，因此适合于研究其他RNA分子伴侣的作用机制。
To satisfy the high demand for ribosome synthesis in rapidly growing eukaryotic cells, short duplexes between the U3 small nucleolar RNA (snoRNA) and the precursor ribosomal RNA (pre-rRNA) must form quickly and with high yield. These interactions, designated the U3-ETS and U3-18S duplexes, are essential to initiate the processing of small subunit rRNA. Previously, we showed in vitro that duplexes corresponding to those in Saccharomyces cerevisiae are only observed after addition of one of two proteins: Imp3p or Imp4p. Here, we used fluorescence-based and other in vitro assays to determine whether these proteins possess RNA chaperone activities and to assess whether these activities are sufficient to satisfy the duplex yield and rate requirements expected in vivo. Assembly of both proteins with the U3 snoRNA into a chaperone complex destabilizes a U3-stem structure, apparently to expose its 18S base-pairing site. As a result, the chaperone complex accelerates formation of the U3-18S duplex from an undetectable rate to one comparable to the intrinsic rate observed for hybridizing short duplexes. The chaperone complex also stabilizes the U3-ETS duplex by 2.7 kcal/mol. These chaperone activities provide high U3-ETS duplex yield and rapid U3-18S duplex formation over a broad concentration range to help ensure that the U3-pre-rRNA interactions limit neither ribosome biogenesis nor rapid cell growth. The thermodynamic and kinetic framework used is general and thus suitable to investigate the mechanism of action of other RNA chaperones.
登录
查看更多内容
影响因子：
11.4
作者：
HUGHES, JMX;KONINGS, DAM;CESARENI, G
通讯作者：
CESARENI, G
影响因子：
11.4
作者：
BELTRAME, M;TOLLERVEY, D
通讯作者：
TOLLERVEY, D
影响因子：
14.9
作者：
Granneman, S;Gallagher, JEG;Pruijn, GJM
通讯作者：
Pruijn, GJM
影响因子：
5.6
作者：
Borovjagin, AV;Gerbi, SA
通讯作者：
Gerbi, SA
影响因子：
16
作者：
Grandi, P;Rybin, V;Hurt, E
通讯作者：
Hurt, E