THE STRUCTURE OF AN EICOSANOID BIOSYNTHETIC COMPLEX

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。 来自Plexaura homomalla的自然产生的8R-脂氧合酶(8R-LOX)和丙二烯氧化物合成酶融合(AOS)蛋白催化生物合成途径中的连续步骤。反应的中间体是花生四烯酸的8R-羟基过氧基衍生物，既疏水又不稳定。为了了解催化活性的组装如何影响反应中间体的转移，从而影响生物合成的效率，我们将确定脂氧合酶-丙二烯氧化物合成酶复合体的结构。我们已经确定了独立表达结构域的晶体结构，并表明它们可以结合成一个异二聚体。此外，我们还证明了钙结合促进了脂氧合酶结构域的膜结合。还提出了解释(1)在催化循环中发生的构象变化和(2)在钙结合时发生的构象变化的实验。

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. A naturally occurring 8R-lipoxygenase (8R-LOX) and allene oxide synthase fusion (AOS) protein from Plexaura homomalla catalyses successive steps in a biosynthetic pathway. The intermediate in the reaction, the 8R-hydroperoxy derivative of arachidonic acid, is both hydrophobic and labile. In order to understand how an assembly of catalytic activities impacts the transfer of the reaction intermediate, and thus the efficiency of biosynthesis, we will determine the structure of the lipoxygenase-allene oxide synthase complex. We have determined the crystal structures of the independently expressed domains, and have shown that they associate into a heterodimer. In addition we have shown that Ca2+ binding promotes membrane binding of the lipoxygenase domain. Experiments to elucidate conformational changes that occur (1) during the catalytic cycle and (2) upon Ca2+ binding are also proposed.