Comparative Glycomics of the HIV Protein gp 120

描述（由申请人提供）：糖蛋白gp120覆盖在HIV病毒表面。它在HIV感染中起着至关重要的作用，因为gp120与体内的受体位点结合，是病毒侵入宿主细胞的第一步。由于这种病毒在不进入宿主细胞的情况下无法增殖，因此治疗艾滋病的主要研究重点是阻止最初的细胞入侵。在细胞入侵之前消灭病毒的策略尚未实现，因为gp120上的碳水化合物对抗体攻击存在屏障。虽然HIV病毒上存在的聚糖已被确定为病毒避免被免疫系统破坏的主要原因，但几乎无法克服病毒的防御机制，即它的聚糖屏蔽，因为对蛋白质上24个糖基化位点上的碳水化合物的了解还不够。我们已经确定了更好地了解病毒防御机制所需的关键信息：1)每个糖基化位点的碳水化合物组成是什么？2)这些位置的拓扑结构（分支的程度）是什么？3)在蛋白质表面，由于带负电荷的碳水化合物，哪里有静电相互作用的潜力？为了回答这些问题，我们将使用先进的质谱仪器，包括MALDI TOF-TOF质谱仪和线性陷阱-傅立叶变换离子回旋共振质谱仪（LTQ-FTMS）来探测糖肽的结构。我们正在开发新的质谱方法来探测gp120中带负电荷的糖型的位置，以及识别糖肽拓扑结构的方法。此外，通过比较不同gp120分离株中这些因素的变化，我们可以确定在不同gp120分离株中，糖蛋白的哪一部分碳水化合物含量变化的倾向最小。这一信息将直接影响gp120的结构-功能模型，并为未来的疫苗靶点提供方向。该项目的合作者包括威奇托州立大学（Wichita State University）的糖生物学家乔治？Mike Alterman和Todd Williams是堪萨斯大学蛋白质组学研究所的联合主任。

DESCRIPTION (provided by applicant): The glycoprotein, gp120, covers the surface of the HIV virus. It plays an essential role in HIV infection, because gp120 binds to receptor sites in the body, as the first step of viral invasion into host cells. Since the virus cannot proliferate without entering host cells, a major thrust of research directed at curing AIDS has focused on stopping the initial cellular invasion. A strategy to destroy the virus prior to cellular invasion has not yet been achieved, because the carbohydrates on gp120 present a barrier to antibody attack. While the glycans present on the HIV virus have been identified as the primary reason that the virus avoids destruction by the immune system, little can be done to overcome the virus's defense mechanism, its glycan shield, because not enough is known about the carbohydrates present at each of the 24 glycosylation sites on the protein. We have identified critical information needed to better understand the virus's defense mechanism: 1) What is the carbohydrate composition at each glycosylation site? 2) What is the topology (the degree of branching) at these sites? 3) Where is there a potential for electrostatic interaction, due to negatively charged carbohydrates, on the surface of the protein? To answer these questions, we will probe glycopeptide structure using advanced mass spectrometric instrumentation, including a MALDI TOF-TOF mass spectrometer and Linear Trap-Fourier Transform Ion Cyclotron Resonance Mass Spectrometer (LTQ-FTMS). We are developing new mass spectrometric methods to probe the location of negatively charged glycoforms within gp120, as well as methods to identify glycopeptide topology. Furthermore, by comparing how each of these factors change from different gp120 isolates, we can determine which portions of the glycoprotein show the least propensity for variation in the carbohydrate content, among the different gp120 isolates. This information will directly impact both structure-function models of gp120, as well as provide direction for future vaccine targets. Collaborators on the project include Dr. George Bousfield, a glycobiologist from Wichita State University, and Drs. Mike Alterman and Todd Williams, Co-Directors of the University of Kansas Proteomics Facility.