Effects of the U1C L13 mutation and temperature regulation of yeast commitment complex formation
Effects of the U1C L13 mutation and temperature regulation of yeast commitment complex formation
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DOI：
10.1073/pnas.0406319101
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发表时间：
2004-10-12
影响因子：
11.1
通讯作者：
Rosbash, M
中科院分区：
文献类型：
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作者：
Du, H;Tardiff, DF;Rosbash, M
U1小核核糖核蛋白颗粒U1 C蛋白在其N末端具有锌指样结构（C2 H2基序），其从酵母到人类都是保守的。该结构域内氨基酸L13的突变拯救了解旋酶蛋白Prp 28 p的基本功能。Prp 28 p参与解旋5'剪接位点（5' ss）-U1小核RNA（snRNA）碱基配对，以允许在剪接体组装期间用U6 snRNA替换U1 snRNA。因此，L13表型被解释为表明WT U1 C通过与RNA双链体结合而有助于5 'ss-U1 snRNA的稳定。我们在这里表明，L13突变体提取物不能在室温下形成稳定的碱基配对，但在低温下允许U1- 5 'ss碱基配对。该表型与WC耗尽提取物的表型相似，表明WC L13突变是一种强烈的功能丧失突变。这两种突变体提取物与WT提取物不同，WT提取物在室温下经历稳定的配对，但在低温下很少或没有配对。与以前的结果和未能观察到U1 C与U1- 5 'SS双链体的直接相互作用一起，数据表明WC在允许条件下间接有助于稳定U1- 5' SS碱基配对。提出了一个模型来解释L13的结果。
The U1 small nuclear ribonucleoprotein particle U1C protein has a zinc finger-like structure (C2H2 motif) at its N terminus, which is conserved from yeast to humans. Mutations of amino acid L13 within this domain rescue the essential function of the helicase protein Prp28p. Prp28p has been implicated in unwinding the 5' splice site (5'ss)-U1 small nuclear RNA (snRNA) base-pairing, to allow replacement of U1 snRNA with U6 snRNA during spliceosome assembly. The L13 phenotype has therefore been interpreted to indicate that WT U1C contributes to 5'ss-U1 snRNA stabilization by binding to the RNA duplex. We show here that an L13 mutant extract cannot form stable base-pairing at room temperature but is permissive for U1-5'ss base-pairing at low temperature. This phenotype is similar to that of a WC-depleted extract, indicating that the WC L13 mutation is a strong loss-of-function mutation. The two mutant extracts are unlike a WT extract, which undergoes stable pairing at room temperature but little or no pairing at low temperature. Taken together with previous results and the failure to observe a direct interaction of U1C with the U1-5'ss duplex, the data suggest that WC contributes indirectly to stable U1-5'ss base-pairing under permissive conditions. A model is proposed to account for the L13 results.