ANALYSIS OF THE MODULAR ARCHITECTURE OF TWO BLOOD GROUP ACTIVE GLYCOSIDE HYDROLA

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。列出的机构是 中心，不一定是研究者的机构。 肺炎链球菌是人类胃肠道的显著定殖者。 其分泌的毒力因子的主要组分是碳水化合物活性酶，其是大的、多模块的，并且参与从宿主组织收获和加工聚糖。我们已经选择了两个家庭98糖苷水解酶的特性，这是积极的人血型抗原。 我们已经解决了高分辨率结构的所有个别模块使用X-射线结晶，然而，全长酶的结晶已被证明是棘手的。为了构建实验证明的整个酶的工作模型，基于来自这些酶的各个模块化构建体的3D结构，我们正在SSRL的光束线4-2上申请SAXS实验。该方法提供了一种独立地确定模块的相对取向的方式，并且有助于基于由该方法确定的低分辨率溶液结构来构建模型。正如最近在几个案例中成功地表明的那样，全长酶的结构研究可以通过溶液中的SAXS测量来实现。这让我们看到了关于催化和粘附的一些有趣的方面。

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. Streptococcus pneumoniae is a notable colonizer of the human gastrointestinal tract. A major component of its secreted virulence factors are carbohydrate active enzymes which are large, multi-modular, and involved in harvesting and processing glycans from host tissues. We have chosen two family 98 glycoside hydrolases for characterization which are active on human blood group antigens. We have solved the high resolution structures of all the individual modules using x-ray crystallization; however, crystallization of the full length enzyme has proven intractable. In order to construct an experimentally proven working model of the whole enzyme, based on the 3D structures of the individual modular constructs from these enzymes, we are applying for SAXS experiments at the SSRL on beam line 4-2. This method provides a way of independently determining the relative orientations of the modules and helping to build a model based on the low resolution solution structure determined by this method. As has been shown successfully in several cases recently, the structural study of full-length enzymes can be attained by SAXS measurements in solution. This allows us to see some interesting aspects regarding catalysis and adherence.