Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Canada.
Department of Molecular Genetics, University of Toronto, Toronto, Canada.
Life Sci Alliance. 2022 May 5;5(8). doi: 10.26508/lsa.202101358. Print 2022 Aug.
In the human fungal pathogen , encodes an essential multi-enzyme that catalyses consecutive steps in the shikimate pathway for biosynthesis of chorismate, a precursor to folate and the aromatic amino acids. We obtained the first molecular image of Aro1 that reveals the architecture of all five enzymatic domains and their arrangement in the context of the full-length protein. Aro1 forms a flexible dimer allowing relative autonomy of enzymatic function of the individual domains. Our activity and in cellulo data suggest that only four of Aro1's enzymatic domains are functional and essential for viability of , whereas the 3-dehydroquinate dehydratase (DHQase) domain is inactive because of active site substitutions. We further demonstrate that in , the type II DHQase Dqd1 can compensate for the inactive DHQase domain of Aro1, suggesting an unrecognized essential role for this enzyme in shikimate biosynthesis. In contrast, in and , which do not encode a Dqd1 homolog, Aro1 DHQase domains are enzymatically active, highlighting diversity across species.
在人类真菌病原体中， 编码一种必需的多酶，它催化莽草酸途径中的连续步骤，用于生物合成磷酸吡哆醛和芳香族氨基酸的前体物质——分支酸。我们获得了 Aro1 的第一个分子图像，揭示了所有五个酶结构域的结构及其在全长蛋白质中的排列方式。Aro1 形成一个灵活的二聚体，允许各个结构域的酶功能相对自主。我们的活性和细胞内数据表明，只有 Aro1 的四个酶结构域对于 的生存能力是功能性和必需的，而 3-脱氢奎宁酸脱水酶（DHQase）结构域由于活性位点取代而失活。我们进一步证明，在 中，类型 II DHQase Dqd1 可以补偿 Aro1 中失活的 DHQase 结构域，这表明该酶在莽草酸生物合成中具有未被认识的重要作用。相比之下，在 和 中，它们不编码 Dqd1 同源物，Aro1 的 DHQase 结构域具有酶活性，突出了 种间的多样性。
