FACTORS INFLUENCING GENETIC TRANSCRIPTION INITIATION AND TERMINATION

该实验室继续对核糖核酸酶H进行研究。这些酶是 对研究艾滋病毒等逆转录病毒感染以及 信使反义降解参与治疗 核糖核酸。此外，这些蛋白质在生物化学中占有独特的地位。 研究是因为它们能够区分RNA-DNA和 RNA-RNA双链，并降解RNA-DNA杂交物的RNA部分。这个 这一认可和歧视的细节将推动我们的 了解蛋白质与核相互作用的机制 酸。 我们已经证明，在细菌中发现的两种类型的RNases H也是 存在于真核生物中。这些都是重要的发现，因为他们的 可能参与反义药物治疗和评估 HIV核糖核酸酶H抑制剂对细胞功能的影响 细胞核糖核酸酶H. 我们还定义了一个非RNaseH结构域存在于一类 与双链RNA结合的真核RNase H，可能作为一种手段 核糖核酸酶H活性的调节。一个由40个氨基酸组成的常见基序是 存在于这一类的所有真核酶中，包括酵母和 人类细胞。有趣的是，一种参与翻译的蛋白质 花椰菜花叶病毒的多顺反子mRNA具有相同的基序和 当放置在酵母RNase H的环境中时，其功能是RNA 双链结合位点。这表明每个设备都能识别双工RNA 这些蛋白质中。这个非RNaseH结构域提供了一个机会 定义蛋白质上两个结构域中与RNA-DNA结合的位点 杂交体，从而提供了对蛋白质核的重要洞察 酸的相互作用。纯化到均一的这类核糖核酸酶H具有 与各种表面结合的不良特性，并且很容易 迷路了。然而，当包括双链RNA时，蛋白质会与它们结合 并保持可溶状态。可以利用此属性来确定 结合所需的最小双链RNA大小并提供潜在的 获得用于测定的蛋白质和核酸的共晶 用X射线结晶学对其结构进行了分析。

The lab has continued studies on ribonucleases H. These enzymes are important for studying retroviral infections such as HIV as well as participation in therapy by means of antisense degradation of messenger RNA. In addition, these proteins occupy a unique niche in biochemical studies because of their ability to distinguish between RNA-DNA and RNA-RNA duplexes and degrade the RNA moiety of RNA-DNA hybrids. The details of this recognition and discrimination will advance our understanding of mechanisms by which proteins interact with nucleic acids. We have shown that two types of RNases H found in bacteria also are present in eukaryotes. These are important findings in light of their potential involvement in antisense drug therapy and for assessment of inhibitors of HIV RNase H on cell functions resulting from inhibition of cellular RNases H. We have also defined a non-RNase H domain present on one class of eukaryotic RNases H that binds to duplex RNAs, possibly as a means of regulation of RNase H activity. A common motif of 40 amino acids is present in all eukaryotic enzymes of this class including yeasts and human cells. Interestingly, a protein involved in translation of the polycistronic mRNA of cauliflower mosaic virus has the same motif and when placed in the context of the yeast RNase H, functions as an RNA duplex binding site. This points to recognition of duplex RNAs by each of these proteins. This non-RNase H domain provides an opportunity to define the sites on the protein, in both domains, that bind to RNA-DNA hybrids and, thereby, provide significant insight into protein nucleic acid interactions. RNase H of this class purified to homogeneity has the undesirable property of binding to various surfaces and can easily be lost. However, when duplex RNAs are included, the protein binds to them and remains soluble. This property can be exploited to determine the minimum size of duplex RNA necessary for binding and offers the potential for obtaining co-crystals of protein and nucleic acid for determination of the structure by X-ray crystallography.