Dual functionality of O-GlcNAc transferase is required for Drosophila development.
Dual functionality of O-GlcNAc transferase is required for Drosophila development.
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DOI：
10.1098/rsob.150234
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发表时间：
2015-12
期刊：
影响因子：
5.8
通讯作者：
van Aalten DM
中科院分区：
文献类型：
--
作者：
Mariappa D;Zheng X;Schimpl M;Raimi O;Ferenbach AT;Müller HA;van Aalten DM
O-GlcNAc转移酶（OGT）催化的O-连接N-乙酰葡糖胺（O-GlcNAc）对细胞内蛋白质的翻译后修饰与多种细胞功能的调节有关。OGT具有参与蛋白质-蛋白质相互作用的C-末端糖基转移酶催化结构域和N-末端三肽重复序列。果蝇OGT（DmOGT）基因由超级性梳（super sex combs，sxc）编码，其突变体对蛹具有致死性。然而，尚不清楚这种表型是否是由O-GlcNAc酰化减少引起的。在这里，我们使用遗传学的方法来证明蛹后果蝇的发展可以进行可以忽略不计的OGT催化，而早期胚胎发育是OGT活性依赖。人OGT（hOGT）和DmOGT之间的结构和酶的比较告知DmOGT点突变体的合理设计与一系列降低催化活性。引人注目的是，一个严重的亚型OGT突变体补充sxc蛹致死。然而，亚型OGT突变体拯救的后代不产生F2成体，因为一组Hox基因在F2胚胎中被去抑制，导致同源异型表型。因此，OGT催化活性需要到后期蛹阶段，而进一步的发展过程中，OGT活性严重降低。
Post-translational modification of intracellular proteins with O-linked N-acetylglucosamine (O-GlcNAc) catalysed by O-GlcNAc transferase (OGT) has been linked to regulation of diverse cellular functions. OGT possesses a C-terminal glycosyltransferase catalytic domain and N-terminal tetratricopeptide repeats that are implicated in protein–protein interactions. Drosophila OGT (DmOGT) is encoded by super sex combs (sxc), mutants of which are pupal lethal. However, it is not clear if this phenotype is caused by reduction of O-GlcNAcylation. Here we use a genetic approach to demonstrate that post-pupal Drosophila development can proceed with negligible OGT catalysis, while early embryonic development is OGT activity-dependent. Structural and enzymatic comparison between human OGT (hOGT) and DmOGT informed the rational design of DmOGT point mutants with a range of reduced catalytic activities. Strikingly, a severely hypomorphic OGT mutant complements sxc pupal lethality. However, the hypomorphic OGT mutant-rescued progeny do not produce F2 adults, because a set of Hox genes is de-repressed in F2 embryos, resulting in homeotic phenotypes. Thus, OGT catalytic activity is required up to late pupal stages, while further development proceeds with severely reduced OGT activity.