Vasserot A P, Schaufele F J, Birnstiel M L
Research Institute of Molecular Pathology, Vienna, Austria.
Proc Natl Acad Sci U S A. 1989 Jun;86(12):4345-9. doi: 10.1073/pnas.86.12.4345.
The hairpin loop structure and the downstream spacer element of histone mRNA precursors are both needed for efficient 3' end formation in vivo and in vitro. Though generally considered as a single processing signal, these two motifs are involved in different types of interaction with the processing machinery. Whereas RNA duplex formation between the downstream spacer element and the U7 small nuclear RNA is essential for processing, we show here that base pairing between the histone stem-loop structure and the U7 RNA is not relevant. Our experiments demonstrate that a processing factor other than the U7 RNA makes contact with the highly conserved hairpin structure of the histone precursor. The recognition of the target site by the processing factor is structure and sequence specific. Prevention of this interaction results in an 80% decrease of 3' cleavage efficiency in vitro. The hairpin binding factor is Sm-precipitable and can be partially separated from the U7 small nuclear ribonucleoprotein particle on a Mono Q column.
组蛋白mRNA前体的发夹环结构和下游间隔元件对于体内和体外高效的3'端形成都是必需的。尽管通常被视为单一的加工信号，但这两个基序与加工机制的相互作用类型不同。虽然下游间隔元件与U7小核RNA之间形成RNA双链体对于加工至关重要，但我们在此表明组蛋白茎环结构与U7 RNA之间的碱基配对并不相关。我们的实验表明，除U7 RNA之外的一种加工因子与组蛋白前体的高度保守发夹结构发生接触。加工因子对靶位点的识别具有结构和序列特异性。阻止这种相互作用会导致体外切割效率降低80%。发夹结合因子可被Sm沉淀，并且在Mono Q柱上可与U7小核核糖核蛋白颗粒部分分离。
