DIFFRACTION OF BACTERIAL ENDOTOXINS: STRUCT BASED DRUG DESIGN, SCREEN PCP ENZYME

细菌内毒素的衍射：基于结构的药物设计，筛选 PCP 酶

• 批准号: 6339116
• 负责人: Vivian Cody
• 金额: $ 1.38万
• 依托单位: CORNELL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-08-15 至 2001-08-14
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6339116
• 关键词: bioimaging /biomedical imaging; biological products; biomedical resource; proteins; radiography; structural biology

Delta endotoxins are the entomocidal agent produced by Bacillus thuringiensis ssp. Kurstaki. These toxins are produced as protoxins (135 kDa) by the bacteria during sporulation and recognized by their bipyrimidal crystalline form in the sporangium. When ingested by larval Lepidoptera the crystal dissolves and is proteolytically digested to the active toxin form (60-65 kDa). This activated toxin is capable of opening K+ channels in the epithelium of the insect midgut. Ion leakage ultimately results in the complete disruption of the midgut and death of the insect. More recently, a new active form of the toxin, CryIIIB2, has been determined (64 kDa). The bacterial endotoxin CryIIIB2 is a 652 residue protein which crystallizes in the orthorhombic space group C2221 with unit cell dimensions a = 122.44, b = 131.81, and c = 105.37& and contain one molecule in the asymmetric unit. Synchrontron radiation was used to collect 2.2& resolution data at the CHESS facility at Cornell University in December, 1997 by Vivian Cody and Nikolai Galitsky for the complex of EC11095 with D-galactosamine. Although these data were did not diffract uniformly to high resolution, Walt Pangborn was able to scale data with at least 50% completion for all shells to 2.2& resolution. The structure of the native CryIIIB2 was used as a search model for the rotation and translation function in the program XPLOR which revealed there was no significant change in the molecular orientation of the molecule compared to the room temperature model. The major consequence of low temperature data collection is the contraction of the unit cell along the a and b lattice directions. Interpretation of the difference electron density maps made from the 3.0& refinement model of the Arg-348 mutant of CryIIIB2 revealed a large density profile that clearly was not a cluster of solvent and that could be fit to the sugar. These data reveal that the galactosamine is positioned at the intersection of the three domains of CryIIIB2. Refinement of these data to 2.2& resolution suggest other potential sugar binding sites are possible.

三角洲内毒素是芽孢杆菌产生的昆虫固定剂 苏云金SSP。 库尔施塔基。 这些毒素作为素毒素产生 （135 kDa）由细菌在孢子形成过程中被细菌识别 孢子囊中的二吡啶晶体形式。 摄入时 幼虫鳞翅目晶体溶解并蛋白水解 消化为活性毒素形式（60-65 kDa）。 这激活了毒素 能够在昆虫上皮中打开K+通道 Midgut。 离子泄漏最终导致完全破坏 昆虫的中肠和死亡。 最近，一种新的活跃形式 已经确定了毒素的cryiiib2（64 kDa）。 细菌 内毒素cryiiib2是一种652个残基蛋白，在 具有单元尺寸a = 122.44，b = 131.81，C = 105.37＆，并在不对称中包含一个分子 单元。 同步辐射用于收集2.2和分辨率数据 1997年12月在康奈尔大学的国际象棋设施 Vivian Cody和Nikolai Galitsky，用于EC11095的综合体 D-半乳糖胺。 尽管这些数据不是均匀衍射的 高分辨率，Walt Pangborn能够至少使用 所有壳到2.2＆分辨率的50％完成。 结构 本机cryiiib2用作旋转的搜索模型， Xplor中的翻译功能，该功能显示没有 分子的分子取向的显着变化 与室温模型相比。 低的主要结果 温度数据收集是沿着单位电池的收缩 A和B晶格指示。 差异的解释 电子密度图由3.0和改进模型制成 Arg-348 cryiiib2突变体显示出较大的密度曲线 显然不是溶剂簇，可以适合 糖。 这些数据表明，半乳糖胺位于 Cryiiib2的三个域的交点。 这些精炼 数据到2.2＆分辨率提示其他潜在的糖结合位点 可能。