Evolutionarily conserved structural changes in phosphatidylinositol 5-phosphate 4-kinase (PI5P4K) isoforms are responsible for differences in enzyme activity and localization.
Evolutionarily conserved structural changes in phosphatidylinositol 5-phosphate 4-kinase (PI5P4K) isoforms are responsible for differences in enzyme activity and localization.
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DOI：
10.1042/bj20130488
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发表时间：
2013-08-15
期刊：
影响因子：
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通讯作者：
Irvine RF
中科院分区：
文献类型：
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作者：
Clarke JH;Irvine RF
哺乳动物有三个编码PI5P4K(PtdIns5P4-Kinase)的基因，这些PI5P4Ks具有不同的细胞定位、组织分布和脂激酶活性。在本论文中，我们描述了人类PI5P4Ksα，β和γ以及它们的苍蝇和蠕虫同源物的详细分子探索，以了解这些差异是如何以及为什么产生的。这三种异构体的固有ATPase活性非常相似，我们发现它们G-环区的差异可以解释它们在脂激酶活性上的巨大差异。我们还对PI5P4K家族进行了广泛的电子进化研究，实验表明，秀丽线虫和黑腹果蝇的单一PI5P4K同源物在活性上与最不同的哺乳动物亚型一样差异很大。最后，我们证明了PI5P4Ksα和γ的紧密缔合是真正的异二聚化，而不是同源二聚体的高度寡聚缔合。我们揭示了结构模型与此以及我们早先在PI5P4Kα和PI5P4Kβ之间观察到的明显随机的异二聚化是一致的[Wang，Bond，Letcher，Richardson，Lilley，Irvine和Clarke(2010年)，Biochem。J.430,215-221]。总体而言，哺乳动物PI5P4K的分子多样性解释了它们的许多特性和行为，但它们的生理功能仍然难以捉摸。
Mammals have genes coding for three PI5P4Ks (PtdIns5P 4-kinases), and these have different cellular localizations, tissue distributions and lipid kinase activities. We describe in the present paper a detailed molecular exploration of human PI5P4Ks α, β and γ, as well as their fly and worm homologues, to understand how and why these differences came to be. The intrinsic ATPase activities of the three isoforms are very similar, and we show that differences in their G-loop regions can account for much of their wide differences in lipid kinase activity. We have also undertaken an extensive in silico evolutionary study of the PI5P4K family, and show experimentally that the single PI5P4K homologues from Caenorhabditis elegans and Drosophila melanogaster are as widely different in activity as the most divergent mammalian isoforms. Finally we show that the close association of PI5P4Ks α and γ is a true heterodimerization, and not a higher oligomer association of homodimers. We reveal that structural modelling is consistent with this and with the apparently random heterodimerization that we had earlier observed between PI5P4Kα and PI5P4Kβ [Wang, Bond, Letcher, Richardson, Lilley, Irvine and Clarke (2010), Biochem. J. 430, 215–221]. Overall the molecular diversity of mammalian PI5P4Ks explains much of their properties and behaviour, but their physiological functionality remains elusive.