Zillmann M, Gorovsky M A, Phizicky E M
Department of Biology, University of Rochester, New York 14627.
J Biol Chem. 1992 May 25;267(15):10289-94.
We have previously shown that HeLa cells contain activities implicated in tRNA splicing in yeast, a ligase capable of joining tRNA half-molecules and an NAD-dependent activity capable of removing the 2'-phosphate created at the splice junction by the ligase (Zillmann, M., Gorovsky, M.A., and Phizicky, E.M. (1991) Mol. Cell. Biol. 11, 5410-5416). We show here that removal of the splice junction 2'-phosphate is, as in yeast, a 2'-phosphate-specific phosphotransfer reaction that produces the same, as yet unidentified, small molecule. This enzyme is highly specific for oligomeric substrates having internal 2'-phosphates. Oligomers bearing terminal 2'-phosphates are at least 50-fold less reactive and those bearing 5'- or 3'-terminal phosphates are at least 600-fold less reactive. The requirement for an internal 2'-phosphate can be satisfied by a substrate as small as a dimer.
我们之前已经表明，HeLa细胞含有与酵母中tRNA剪接相关的活性，一种能够连接tRNA半分子的连接酶和一种依赖NAD的活性，该活性能够去除连接酶在剪接位点产生的2'-磷酸（齐尔曼，M.，戈罗夫斯基，M.A.，和菲齐基，E.M.（1991年）《分子与细胞生物学》11，5410 - 5416）。我们在此表明，与酵母一样，去除剪接位点的2'-磷酸是一种2'-磷酸特异性磷酸转移反应，产生相同的、尚未鉴定的小分子。这种酶对具有内部2'-磷酸的寡聚底物具有高度特异性。带有末端2'-磷酸的寡聚物反应活性至少低50倍，而带有5'-或3'-末端磷酸的寡聚物反应活性至少低600倍。对内部2'-磷酸的要求可以由小至二聚体的底物满足。
