Shanmugabalaji Venkatasalam, Grimm Bernhard, Kessler Felix
Laboratory of Plant Physiology, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland.
Institute of Biology/Plant Physiology, Humboldt University Berlin, Berlin, Germany.
Front Plant Sci. 2020 Jan 31;11:2. doi: 10.3389/fpls.2020.00002. eCollection 2020.
Heme plays an active role in primary plant metabolic pathways as well as in stress signaling. In this study, we characterized the predicted heme-binding protein SOUL4. Proteomics evidence suggests that SOUL4 is a component of plastoglobules (PGs, chloroplast lipid droplets). SOUL4 contains heme-binding motifs and the recombinant protein is shown here to bind heme . Fluorescence-tagged SOUL4 colocalized with the specific PG marker Fibrillin1A (FBN1A) in transiently transformed leaves. In addition, SOUL4 cofractionated with another PG marker Fibrillin2 (FBN2) in sucrose gradient ultracentrifugation experiments. kinase experiments revealed that SOUL4 is phosphorylated by a yet unknown chloroplast protein kinase. Our data demonstrate that SOUL4 is a PG protein and may function in heme-buffering in the chloroplast.
血红素在植物初级代谢途径以及应激信号传导中发挥着积极作用。在本研究中，我们对预测的血红素结合蛋白SOUL4进行了表征。蛋白质组学证据表明，SOUL4是质体小球（PGs，叶绿体脂质小滴）的一个组成部分。SOUL4含有血红素结合基序，此处显示重组蛋白可结合血红素。荧光标记的SOUL4在瞬时转化的叶片中与特定的PG标记物原纤维蛋白1A（FBN1A）共定位。此外，在蔗糖梯度超速离心实验中，SOUL4与另一个PG标记物原纤维蛋白2（FBN2）共分级分离。激酶实验表明SOUL4被一种未知的叶绿体蛋白激酶磷酸化。我们的数据表明，SOUL4是一种PG蛋白，可能在叶绿体中的血红素缓冲中发挥作用。
