FACTORS INFLUENCING GENETIC TRANSCRIPTION INITIATION AND TERMINATION

逆转录酶中的核糖核酸酶H与细胞核糖核酸酶H相关 蛋白质，结构上和酶上。 然而，它们的不同之处在于 几个方面。 设计实验以确定序列和 导致两种类型之间差异的结构 RNA酶H一直是我们一些项目的重点。 我们已经表达了 RNA酶H结构域的HIV和MuLV作为单独的蛋白质，并研究了一些 其性质与结合RNA-DNA杂合体有关。 E.大肠杆菌RNase HI 比任何一种核糖核酸酶的酶活性都高1,000倍以上 H来源于哺乳动物逆转录病毒。 E.大肠杆菌RNase HI结合非常 如MuLV RNase H那样迅速地转化为RNA-DNA杂交体。 因此 这两种酶之间的比活性差异是由于 催化活性的差异。 相比之下，E.大肠杆菌核糖核酸酶H 已知负责与蛋白质相互作用的区域缺失的蛋白质 RNA-DNA底物（使其类似于HIV RNase H）结合非常差 到它的基底上。 当我们瞄准E。大肠杆菌RNase H对哺乳动物 逆转录病毒和酵母逆转录转座子，酶的差异 特性导致MuLV、TY-1病毒增殖的抑制 可能还有艾滋病病毒 因此，将细胞RNA酶H靶向病毒颗粒 可能是一种遏制逆转录病毒感染的有效方法。

Ribonuclease H of reverse transcriptase and cellular RNases H are related proteins, both structurally and enzymatically. However, they differ in several aspects. Experiments designed to determine the sequences and structures that contribute to the differences between the two types of RNases H have been a focus of some of our project. We have expressed the RNase H domains of HIV and MuLV as separate proteins and studied some of its properties related to binding to RNA-DNA hybrids. E. coli RNase HI is more than 1,000 times as active enzymatically as either of the RNases H derived from the mammalian retroviruses. E. coli RNase HI binds very rapidly to RNA-DNA hybrids as does the MuLV RNase H. Thus, the differences in specific activity between these two enzymes is due to a difference in catalytic activity. In contrast, an E. coli RNase H protein deleted for the region known to be responsible interacting with RNA-DNA substrates (making it similar to HIV RNase H) binds very poorly to its substrate. When we target E. coli RNase H to mammalian retroviruses and yeast retrotransposons, differences in enzymatic properties result in inhibition of viral multiplication for MuLV, TY-1 and possibly HIV. Thus, targeting of cellular RNase H to virus particles may be a useful method for containing retroviral infections.