tRNA Splicing

tRNA剪接对于某些细胞的生存至关重要， 真核生物。 tRNA剪接的机制是高度 在真核生物中保守，在酵母中最好理解 酿酒酵母 从表面上看， 简单的;内切核酸酶切除内含子;连接酶连接 两个半分子;和2 '-脱磷酸化活性去除 剪接点处的2 '-磷酸 然而， 拼接，特别是最后一步，要多得多 比想象中复杂 拆下接头 连接2 '-磷酸酶，而不是由一个 磷酸酶，由NAD依赖性的2 '-磷酸酶催化 特异性磷酸转移酶。 像这样的蛋白质 已经描述过了，但它可能是必不可少的，如果不是全部， 真核生物来制造功能性的tRNA。 而且 来自tRNA剪接点的磷酸盐最终 作为NAD或类似于NAD的分子上的环状磷酸。 这种分子以前也没有描述过。 的 该提案的目的是识别蛋白质 催化这一不寻常但重要的去磷酸化步骤， tRNA剪接，并确定结构（和机制， 形成）的不寻常的磷酸转移产物。 %%% 处理新合成的转移RNA（tRNA）的过程， 酵母是必需的tRNA的作用，在合成一个 蛋白 处理的一个重要部分涉及编辑出 特定的碱基序列。 本研究 涉及一种关闭tRNA链中缺口的酶（很像 列车汽车在车厢内的汽车之后连接起来的过程。 中心已拆除）。 这种酶具有一些新的特性 这值得研究，以区别于其他结扎 内切酶 从这些研究中得到的信息将是新的 因为这项研究是原创性的。

tRNA splicing is essential for the survival of some, if not all, eukaryotes. The mechanism of tRNA splicing is highly conserved in eukaryotes, and best understood in the yeast Saccharomyces cerevisiae. Superficially, tRNA splicing appears simple; an endonuclease excises the intron; a ligase joins the two half-molecules; and a 2'-dephosphorylating activity removes the 2'-phosphate left at the splice junction. Yet the mechanism of splicing, particularly of the last step, is much more complicated than one would imagine. Removal of the splice junction 2'-phosphatase, rather than being catalyzed by a phosphatase, is catalyzed by an NAD-dependent, 2'-phosphate specific phosphotransferase. A protein like this has never been described, yet it is likely essential in some, if not all, eukaryotes in order to make functional TRNA. Moreover, the phosphate from the splice junction of TRNA ultimately ends up as a cyclic phosphate on NAD, or on a molecule similar to NAD. Such a molecule has also not been previously described. The objects of this proposal are to identify the proteins catalyzing this unusual but important dephosphorylation step in TRNA splicing and to determine the structure (and mechanism of formation) of the unusual phosphotransfer product. %%% The process of processing newly synthesized transfer RNA (TRNA) in yeast is essential for the TRNA to act in the synthesis of a protein. A significant part of the processing involves editing out particular sequences of bases in the strand. This research involves an enzyme which closes a gap in the TRNA strand (much like the process by which train cars are linked up after the cars in the center have been removed). The enzyme has some novel properties which merit investigation to distinguish it from other ligating enzymes . The information resulting from these studies will be new and important since the research is original.