Department of Biochemistry and Molecular Biology, University of Nevada, 1664 N. Virginia St., Reno, NV 89557, USA.
Department of Biochemistry & Center for Plant Science Innovation, University of Nebraska, 1901 Vine St. Lincoln, NE 68588, USA.
Glycobiology. 2024 Apr 24;34(6). doi: 10.1093/glycob/cwae035.
Cellulose is an abundant component of plant cell wall matrices, and this para-crystalline polysaccharide is synthesized at the plasma membrane by motile Cellulose Synthase Complexes (CSCs). However, the factors that control CSC activity and motility are not fully resolved. In a targeted chemical screen, we identified the alkylated nojirimycin analog N-Dodecyl Deoxynojirimycin (ND-DNJ) as a small molecule that severely impacts Arabidopsis seedling growth. Previous work suggests that ND-DNJ-related compounds inhibit the biosynthesis of glucosylceramides (GlcCers), a class of glycosphingolipid associated with plant membranes. Our work uncovered major changes in the sphingolipidome of plants treated with ND-DNJ, including reductions in GlcCer abundance and altered acyl chain length distributions. Crystalline cellulose content was also reduced in ND-DNJ-treated plants as well as plants treated with the known GlcCer biosynthesis inhibitor N-[2-hydroxy-1-(4-morpholinylmethyl)-2-phenyl ethyl]-decanamide (PDMP) or plants containing a genetic disruption in GLUCOSYLCERAMIDE SYNTHASE (GCS), the enzyme responsible for sphingolipid glucosylation that results in GlcCer synthesis. Live-cell imaging revealed that CSC speed distributions were reduced upon treatment with ND-DNJ or PDMP, further suggesting an important relationship between glycosylated sphingolipid composition and CSC motility across the plasma membrane. These results indicate that multiple interventions compromising GlcCer biosynthesis disrupt cellulose deposition and CSC motility, suggesting that GlcCers regulate cellulose biosynthesis in plants.
纤维素是植物细胞壁基质的丰富成分，这种准晶多糖由运动的纤维素合酶复合物（CSC）在质膜上合成。然而，控制 CSC 活性和运动的因素尚未完全解决。在靶向化学筛选中，我们发现烷基化的去氧野尻霉素类似物 N-十二烷基去氧野尻霉素（ND-DNJ）是一种严重影响拟南芥幼苗生长的小分子。先前的工作表明，ND-DNJ 相关化合物抑制葡糖基神经酰胺（GlcCers）的生物合成，GlcCers 是一类与植物膜相关的糖脂。我们的工作揭示了 ND-DNJ 处理的植物鞘脂组发生了重大变化，包括 GlcCer 丰度降低和酰基链长分布改变。在 ND-DNJ 处理的植物以及用已知的 GlcCer 生物合成抑制剂 N-[2-羟基-1-（4-吗啉基甲基）-2-苯基乙基]-癸酰胺（PDMP）处理的植物或含有 GLUCOSYLCERAMIDE SYNTHASE（GCS）基因破坏的植物中，结晶纤维素含量也降低，GCS 是负责糖基化鞘脂的酶，导致 GlcCer 合成。活细胞成像显示，CSC 速度分布在 ND-DNJ 或 PDMP 处理后降低，这进一步表明糖基化鞘脂组成与 CSC 跨质膜运动之间存在重要关系。这些结果表明，多种干扰 GlcCer 生物合成的干预措施会破坏纤维素沉积和 CSC 运动，表明 GlcCers 调节植物中的纤维素生物合成。
