Insights into topology and membrane interaction characteristics of plastoglobule-localized AtFBN1a and AtLOX2
Insights into topology and membrane interaction characteristics of plastoglobule-localized AtFBN1a and AtLOX2
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DOI：
10.1080/15592324.2021.1945213
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发表时间：
2021-06-28
影响因子：
2.9
通讯作者：
Lundquist, Peter K.
中科院分区：
文献类型：
--
作者：
Espinoza-Corral, Roberto;Herrera-Tequia, Andres;Lundquist, Peter K.
植物叶绿体中普遍存在着称为质体小分子的脂滴。虽然物理连接到类囊体膜，他们的特点是一套独特的约30蛋白质特异性与质体小球。这些蛋白质如何选择性地靶向质体小球仍然是未知的。用分离的拟南芥类囊体和质体小球进行的蛋白酶切分析表明，一个约。质体小分子丰富的结构蛋白原纤蛋白1a的25 kD部分被保护免受蛋白酶消化。蛋白酶切割位点和实验鉴定的磷酸化位点映射到原纤蛋白1a的同源性模型上表明，这种受保护的序列对应于C-末端脂质运载蛋白样结构域，涉及特异性脂质结合。相比之下，蛋白酶剃须和膜洗涤试验与另一个plastoglobule相关蛋白窝藏的C-末端PLAT结构域，脂氧合酶2，是一致的暴露的PLAT结构域定位平行，并在plastoglobule的表面上。我们提出了一个模型，其中保守的脂质结合结构域与表面或中性核心的脂滴。我们的研究提供了深入了解的拓扑结构和膜相互作用的两个plastoglobule本地化的蛋白质。
Plant chloroplasts harbor ubiquitous lipid droplets called plastoglobules. While physically connected to the thylakoid membrane, they are characterized by a unique set of about 30 proteins specifically associated with the plastoglobule. How these proteins selectively target the plastoglobule remains unknown. Protease shaving assays with isolated Arabidopsis thaliana thylakoid and plastoglobule show that a ca. 25 kD portion of the abundant structural protein of plastoglobules, Fibrillin 1a, is protected from protease digestion. Mapping of protease cleavage sites and experimentally identified phosphorylation sites onto a homology model of Fibrillin 1a indicates that this protected sequence corresponds to the C-terminal lipocalin-like domain, implicated in specific lipid binding. In contrast, protease shaving and membrane washing assays with another plastoglobule-associated protein harboring a C-terminal PLAT domain, Lipoxygenase 2, is consistent with an exposed PLAT domain positioned parallel with, and upon, the surface of the plastoglobule. We propose a model where conserved lipid-binding domains associate with either the surface or neutral core of the lipid droplet. Our study provides insight into the topology and membrane interactions of two plastoglobule-localized proteins.