tRNA Splicing in Yeast

内含子是如何从酵母中的tRNA分子中拼接出来的 酿酒酵母？ tRNA剪接在酵母中是必不可少的。 酵母中tRNA剪接的研究是一个范例， 由于剪接的机制是 在这些生物体中高度保守。 剪接涉及切除 一种是通过核酸内切酶，将所得的半- 分子，并去除留在连接酶的2 '-磷酸， 剪接点 由于磷酸盐是tRNA 3'端的一个碱基， 反密码子，其去除可能是产生功能性 tRNA。 去除这种2 '-磷酸盐是本提案的主题。 PI最近鉴定并部分纯化了一种蛋白质 可以有效地去除剪接点 从连接的tRNA磷酸。 这种蛋白质是独特的：它是 特异于2 '-磷酸化底物，需要NAD+， 作为磷酸转移酶。 它的活动似乎也是 受到携带tpd 1突变的细胞的影响。他拟 确定NAD+如何用于连接的tRNA的去磷酸化 并鉴定参与该反应的蛋白质。 他还 建议确定TPD 1蛋白如何影响去磷酸化 在细胞中连接的tRNA，并研究的相互作用， 2 '-磷酸转移酶与其他tRNA组分的剪接 机械.

How are introns spliced from tRNA molecules in the yeast Saccharomyces cerevisiae? tRNA splicing is essential in yeast. Study of tRNA splicing in yeast is a paradigm for splicing in a wide variety of organisms since the mechanism of splicing is highly conserved in these organisms. Splicing involves excision of the intron by an endonuclease, ligation of the resultant half- molecules by a ligase, and removal of a 2'-phosphate left at the splice junction. Since this phosphate is one base 3' of the tRNA anticodon its removal is likely necessary to generate functional tRNA. Removal of this 2'-phosphate is the subject of this proposal. The PI has recently identified and partially purified a protein from yeast that can efficiently remove the splice junction phosphate from ligated tRNA. This protein is unique: it is specific for 2'-phosphorylated substrates, requires NAD+ and acts as a phosphotransferase. Its activity also appears to be affected by cells carrying a tpd1 mutation. He proposes to determine how NAD+ is used in dephosphorylation of ligated tRNA and to identify the proteins involved in this reaction. He also proposes to determine how TPD1 protein affects dephosphorylation of ligated tRNA in the cell, and to study the interaction of the 2'-phosphotransferase with other components of the tRNA splicing machinery.