Whitehead Payton, Raza Saad, Miklaszewska Magdalena, Hornung Ellen, Herrfurth Cornelia, Nadella Rohith, Clews Alyssa, Doner Nathan M, Dyer John M, Mullen Robert, Feussner Ivo, Vermaas Josh V, Chapman Kent D
BioDiscovery Institute and Department of Biological Sciences, University of North Texas, Denton, TX 76203, USA.
MSU-DOE Plant Research Laboratory and Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48823, USA.
Plant Cell. 2025 Aug 1;37(8). doi: 10.1093/plcell/koaf115.
Jojoba (Simmondsia chinensis) is a desert shrub with an unusual capacity to store liquid wax esters (WEs) in its seeds instead of triacylglycerols (TAGs) like most oilseed crops. To examine the factors that are important for WE compartmentalization in jojoba, we reconstituted WE biosynthesis and packaging in the leaves of Nicotiana benthamiana. Using this system, we screened jojoba proteins for their ability to support lipid droplet (LD) formation. A specific LIPID DROPLET-ASSOCIATED PROTEIN (LDAP) isoform, ScLDAP1, was identified as a key factor in the efficient compartmentalization of WEs in plant cells. LDAP1 isoforms from other plants (e.g. Arabidopsis thaliana [AtLDAP1]) did not support WE partitioning from the endoplasmic reticulum into LDs, although both AtLDAP1 and ScLDAP1 were targeted specifically to LD monolayer surfaces. ScLDAP1-mediated selective, efficient WE partitioning was facilitated by an amphipathic α-helix near its C-terminus, and mutational analysis identified 1 amino acid residue within this helix that was both necessary and sufficient for proper WE packaging into cytoplasmic LDs. Taken together, our results provide a mechanistic link between the biosynthesis and storage of WEs in plant cells, and will inform future biotechnology strategies for the efficient packaging of various neutral lipid types as demonstrated here for WEs in transgenic seeds.
荷荷巴（Simmondsia chinensis）是一种沙漠灌木，具有非凡的能力，能在其种子中储存液体蜡酯（WEs），而不像大多数油料作物那样储存三酰甘油（TAGs）。为了研究对荷荷巴中WEs区室化重要的因素，我们在本氏烟草叶片中重建了WEs的生物合成和包装过程。利用该系统，我们筛选了荷荷巴蛋白支持脂滴（LD）形成的能力。一种特定的脂滴相关蛋白（LDAP）异构体ScLDAP1，被确定为植物细胞中WEs高效区室化的关键因素。来自其他植物的LDAP1异构体（如拟南芥[AtLDAP1]）不支持WEs从内质网分配到脂滴中，尽管AtLDAP1和ScLDAP1都特异性地靶向脂滴单层表面。ScLDAP1介导的选择性、高效的WEs分配是由其C末端附近的一个两亲性α螺旋促进的，突变分析确定了该螺旋内的一个氨基酸残基，它对于将WEs正确包装到细胞质脂滴中既必要又充分。综上所述，我们的结果提供了植物细胞中WEs生物合成与储存之间的机制联系，并将为未来生物技术策略提供信息，以实现各种中性脂质类型的高效包装，如此处所示的转基因种子中的WEs。
