A Drosophila metallophosphoesterase mediates deglycosylation of rhodopsin
A Drosophila metallophosphoesterase mediates deglycosylation of rhodopsin
复制标题
果蝇金属磷酸酯酶介导视紫红质的去糖基化
DOI：
10.1038/emboj.2011.254
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发表时间：
2011-09-14
期刊：
影响因子：
11.4
通讯作者：
Han, Junhai
中科院分区：
文献类型：
--
作者：
Cao, Jinguo;Li, Yi;Han, Junhai
新合成的膜受体的寡糖链在递送至细胞表面之前被修剪和修饰以优化它们的运输和/或信号传导。对于大多数膜受体，寡糖链修饰的功能意义是未知的。在果蝇光受体Rh 1视紫红质的成熟过程中，寡糖链被广泛修剪。这种修饰的功能意义和介导这一过程的酶都是未知的。在这里，我们确定了dmppe（果蝇金属磷酸酯酶）突变体与不完全去糖基化的Rh 1，并表明保留的寡糖链不影响Rh 1的本地化或信号。不完全去糖基化，然而，使Rh 1更敏感的内吞降解，并导致老年dmppe苍蝇的感光细胞的形态和功能缺陷。我们进一步证明了dMPPE蛋白作为Mn 2 +/Zn 2+依赖性磷酸酯酶发挥作用，并介导体内α-Man-II的去磷酸化。最重要的是，需要去磷酸化的α-Man-II来去除Rh 1寡糖链。这些观察结果表明，膜蛋白的糖基化状态是通过磷酸化/去磷酸化来控制的，而MPPE在这种调节中充当磷酸酯酶。The EMBO Journal（2011）30，3701-3713. doi：10.1038/doj.2011.254; 2011年7月29日在线发布
Oligosaccharide chains of newly synthesized membrane receptors are trimmed and modified to optimize their trafficking and/or signalling before delivery to the cell surface. For most membrane receptors, the functional significance of oligosaccharide chain modification is unknown. During the maturation of Rh1 rhodopsin, a Drosophila light receptor, the oligosaccharide chain is trimmed extensively. Neither the functional significance of this modification nor the enzymes mediating this process are known. Here, we identify a dmppe (Drosophila metallophosphoesterase) mutant with incomplete deglycosylation of Rh1, and show that the retained oligosaccharide chain does not affect Rh1 localization or signalling. The incomplete deglycosylation, however, renders Rh1 more sensitive to endocytic degradation, and causes morphological and functional defects in photoreceptors of aged dmppe flies. We further demonstrate that the dMPPE protein functions as an Mn2+/Zn2+-dependent phosphoesterase and mediates in vivo dephosphorylation of alpha-Man-II. Most importantly, the dephosphorylated alpha-Man-II is required for the removal of the Rh1 oligosaccharide chain. These observations suggest that the glycosylation status of membrane proteins is controlled through phosphorylation/dephosphorylation, and that MPPE acts as the phosphoesterase in this regulation. The EMBO Journal (2011) 30, 3701-3713. doi: 10.1038/emboj.2011.254; Published online 29 July 2011