Sculpting of the spliceosomal branch site recognition motif by a conserved pseudouridine
Sculpting of the spliceosomal branch site recognition motif by a conserved pseudouridine
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DOI：
10.1038/nsb873
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发表时间：
2002-12-01
期刊：
影响因子：
--
通讯作者：
Greenbaum, NL
中科院分区：
文献类型：
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作者：
Newby, MI;Greenbaum, NL
在真核剪接体的组装过程中，将前体(pre)-mRNA内含子的一致序列与U2小核（sn） RNA的短区域配对，形成由7个碱基对组成的互补螺旋，其中有一个未配对的腺苷残基。这种腺苷的2oh，称为分支位点，在剪接的第一步在mrna前5'剪接位点引起亲核攻击。这种配对的另一个特点是在U2 snRNA中几乎与分支位点相对的假尿嘧啶（psi）残基的系统发育保守性。我们发现，与未经修饰的对应体相比，这种psi在酿酒酵母的pre-mRNA分支位点螺旋中的存在诱导了显著改变的建筑景观。psi诱导的结构将亲核试剂置于剪接的第一步可接近的位置。
Pairing of a consensus sequence of the precursor (pre)-mRNA intron with a short region of the U2 small nuclear (sn) RNA during assembly of the eukaryotic spliceosome results in formation of a complementary helix of seven base pairs with a single unpaired adenosine residue. The 2 OH of this adenosine, called the branch site, brings about nucleophilic attack at the pre-mRNA 5' splice site in the first step of splicing. Another feature of this pairing is the phylogenetic conservation of a pseudouridine (psi) residue in U2 snRNA nearly opposite the branch site. We show that the presence of this psi in the pre-mRNA branch-site helix of Saccharomyces cerevisiae induces a dramatically altered architectural landscape compared with that of its unmodified counterpart. The psi-induced structure places the nucleophile in an accessible position for the first step of splicing.