Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China.
University of Chinese Academy of Sciences, Beijing, 100049, China.
Plant Mol Biol. 2022 Sep;110(1-2):1-12. doi: 10.1007/s11103-022-01283-8. Epub 2022 May 29.
AtTIP1 physically and genetically interacts with AtCESA3. AtCESA3 undergoes S-acylation, possibly mediated by AtTIP1, suggesting a specific role of AtTIP1 in cellulose biosynthesis and plant development. S-acylation is a reversible post-translational lipid modification of proteins catalyzed by protein S-acyl transferases (PATs). S-acylation is important for various biological molecular mechanisms including cellulose biosynthesis. Cellulose is synthesized by the cellulose synthase A (CESA) complexes (CSCs) at the plasma membrane. However, specific PAT involving in cellulose biosynthesis has not been identified and the precise mechanism by which PAT regulates the CESAs is largely unknown. Here, we report isolation of tip1-5, an allele of Tip Growth Defective1 (AtTIP1/AtPAT24) with a premature stop codon. tip1-5 genetically interacts with ixr1-2, a point mutant of AtCESA3 which encodes a catalytic subunit of CSC synthesizing primary wall cellulose. We show that AtTIP1 physically interacts with AtCESA3. AtCESA3 undergoes S-acylation, which is possibly mediated by AtTIP1, suggesting a functional relationship between AtTIP1 and AtCESA3. Moreover, the interfascicular fiber cells in the primary inflorescence stems of tip1-5 ixr1-2 double mutant contain thinner cell walls and significantly less crystalline cellulose compared to the single mutants. These results highlight the positive regulation of AtTIP1 in cellulose biosynthesis, and a specific role of AtPAT in plant development.
AtTIP1 与 AtCESA3 在物理上和遗传上相互作用。AtCESA3 发生 S-酰化，可能由 AtTIP1 介导，这表明 AtTIP1 在纤维素生物合成和植物发育中具有特定的作用。S-酰化是一种由蛋白质 S-酰基转移酶（PATs）催化的蛋白质的可逆翻译后脂质修饰。S-酰化对于包括纤维素生物合成在内的各种生物分子机制很重要。纤维素是由质膜上的纤维素合酶 A（CESA）复合物（CSCs）合成的。然而，尚未鉴定出涉及纤维素生物合成的特定 PAT，并且 PAT 调节 CESAs 的精确机制在很大程度上尚不清楚。在这里，我们报告了 tip1-5 的分离，这是一个提前终止密码子的 Tip Growth Defective1（AtTIP1/AtPAT24）等位基因。tip1-5 与 ixr1-2 遗传相互作用，ixr1-2 是 AtCESA3 的点突变体，该基因编码合成初生壁纤维素的 CSC 的催化亚基。我们表明 AtTIP1 与 AtCESA3 在物理上相互作用。AtCESA3 发生 S-酰化，这可能由 AtTIP1 介导，表明 AtTIP1 和 AtCESA3 之间存在功能关系。此外，tip1-5 ixr1-2 双突变体初生花序茎的束间纤维细胞的细胞壁较薄，结晶纤维素明显减少，与单突变体相比。这些结果突出了 AtTIP1 在纤维素生物合成中的正调控作用，以及 AtPAT 在植物发育中的特定作用。
