THE STRUCTURE OF AN EICOSANOID BIOSYNTHETIC COMPLEX

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。天然存在的8r -脂氧合酶（8R-LOX）和烯氧合酶融合（AOS）蛋白催化了生物合成途径的连续步骤。反应中的中间体，花生四烯酸的8r -羟基衍生物，既疏水又不稳定。为了了解催化活性的集合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-氧化烯合酶复合物的结构。我们已经确定了独立表达域的晶体结构，并表明它们结合成异二聚体。此外，我们已经表明Ca2+结合促进脂氧合酶结构域的膜结合。还提出了阐明(1)在催化循环期间和(2)Ca2+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.