PUX10 Is a Lipid Droplet-Localized Scaffold Protein That Interacts with CELL DIVISION CYCLE48 and Is Involved in the Degradation of Lipid Droplet Proteins
PUX10 Is a Lipid Droplet-Localized Scaffold Protein That Interacts with CELL DIVISION CYCLE48 and Is Involved in the Degradation of Lipid Droplet Proteins
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DOI：
10.1105/tpc.18.00276
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发表时间：
2018-09-01
期刊：
影响因子：
11.6
通讯作者：
Ischebeck, Till
中科院分区：
文献类型：
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作者：
Kretzschmar, Franziska K.;Mengel, Laura A.;Ischebeck, Till
与其他细胞器相比，与植物脂滴 (LD) 相关的已知蛋白质数量很少。 LD 生物合成和降解的许多方面都是未知的，识别和表征候选 LD 蛋白可以帮助阐明这些过程。在这里，我们分析了从烟草 (Nicotiana tabacum) 花粉管中分离出的 LD 富集组分的蛋白质组。通过花粉管中的瞬时表达，进一步测试与总部分或胞质部分相比高度富集的蛋白质的 LD 定位。其中一种蛋白质，植物 UBX 结构域蛋白 10 (PUX10)，是植物 UBX 结构域 (PUX) 蛋白家族的成员。该蛋白通过独特的疏水性多肽序列定位于 LD，并可通过其 UBX 结构域招募 AAA 型 ATP 酶细胞分裂周期 48 (CDC48) 蛋白。 PUX10 在拟南芥中保守，并在胚胎、花粉管和幼苗中表达。在拟南芥中的 pux10 敲除突变体中，LD 大小显着增加。 pux10 突变体的蛋白质组学分析揭示了已知 LD 蛋白的延迟降解，其中一些蛋白具有泛素化位点。我们认为 PUX10 参与 LD 的蛋白质降解途径，介导针对降解的多泛素化蛋白质与下游效应子（如 CDC48）之间的相互作用。
The number of known proteins associated with plant lipid droplets (LDs) is small compared with other organelles. Many aspects of LD biosynthesis and degradation are unknown, and identifying and characterizing candidate LD proteins could help elucidate these processes. Here, we analyzed the proteome of LD-enriched fractions isolated from tobacco (Nicotiana tabacum) pollen tubes. Proteins that were highly enriched in comparison with the total or cytosolic fraction were further tested for LD localization via transient expression in pollen tubes. One of these proteins, PLANT UBX DOMAIN-CONTAINING PROTEIN10 (PUX10), is a member of the plant UBX domain-containing (PUX) protein family. This protein localizes to LDs via a unique hydrophobic polypeptide sequence and can recruit the AAA-type ATPase CELL DIVISION CYCLE48 (CDC48) protein via its UBX domain. PUX10 is conserved in Arabidopsis thaliana and expressed in embryos, pollen tubes, and seedlings. In pux10 knockout mutants in Arabidopsis, LD size is significantly increased. Proteomic analysis of pux10 mutants revealed a delayed degradation of known LD proteins, some of which possessed ubiquitination sites. We propose that PUX10 is involved in a protein degradation pathway at LDs, mediating an interaction between polyubiquitinated proteins targeted for degradation and downstream effectors such as CDC48.