IDENTIFYING THE PATH OF THE RNA PRIMER AROUND A SIMPLE RNA POLYMERASE

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 痘苗病毒多(A)聚合酶(VP55)是已知的唯一相对于其RNA引物易位的RNA聚合酶，这引发了一个悖论：聚合酶和引物哪一个更灵活？该蛋白有两种已知的作用模式，即30个核苷酸残基的过程合成和200~300个核苷酸残基的半过程合成。过去的合作研究已经产生了VP39和VP55-VP39异二聚体的晶体结构。最重要的，但缺乏的信息是对异二聚体-引物复合体的结构理解。通过使用一位同事的光束时间，Gershon实验室的一位全职结晶学家在寻找聚合酶表面短RNA片段的结合位点方面取得了显著进展。虽然这是一项突破性的原创性工作，但每两个月3小时的束流时间不足以确保这项由NIH资助的工作的进展，以确保拨款续期。束流时间是主要的瓶颈，因此目前需要单独的、规则的束流时间来进行这项结晶学工作。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Vaccinia virus poly(A) polymerase (VP55) is the only RNA polymerase known to translocate with respect to its RNA primer, raising a paradox: Which is more flexible: The polymerase or the primer? The protein has two known modes of action, namely the processive synthesis of 30 nt tails and, as a heterodimer with its processivity factor (VP39), the semi-processive synthesis of 200 ? 300 nt tails. Past, collaborative studies, have yielded crystal structures for VP39, and for the VP55-VP39 heterodimer. The most important, yet absent information is a structural understanding of the heterodimer-primer complex. By using the beam time of a colleague, a full-time crystallographer in the Gershon lab has progressed markedly in finding binding sites for short RNA segments on the polymerase surface. Although this is ground-breaking, original work for a poly(A) polymerase, 3 hours of beam time every 2 months provides inadequate progress in this NIH-funded work to ensure grant renewal. Beam time is the major bottleneck, hence the current request for individual, regular beam time for this crystallographic work.