Center of Excellence for the Oceans, National Taiwan Ocean University, Keelung 202301, Taiwan.
Department of Bioscience and Biotechnology, National Taiwan Ocean University, Keelung 202301, Taiwan.
Biomolecules. 2024 Mar 19;14(3):372. doi: 10.3390/biom14030372.
Diatoms, efficient carbon capture organisms, contribute to 20% of global carbon fixation and 40% of ocean primary productivity, garnering significant attention to their growth. Despite their significance, the synthesis mechanism of polyamines (PAs), especially spermidine (Spd), which are crucial for growth in various organisms, remains unexplored in diatoms. This study reveals the vital role of Spd, synthesized through the spermidine synthase (SDS)-based pathway, in the growth of the diatom . PtSDS1 and PtSDS2 in the genome were confirmed as SDS enzymes through enzyme-substrate selectivity assays. Their distinct activities are governed primarily by the Y79 active site. Overexpression of a singular gene revealed that PtSDS1, PtSDS2, and PtSAMDC from the SDS-based synthesis pathway are all situated in the cytoplasm, with no significant impact on PA content or diatom growth. Co-overexpression of PtSDS1 and PtSAMDC proved essential for elevating Spd levels, indicating multifactorial regulation. Elevated Spd content promotes diatom growth, providing a foundation for exploring PA functions and regulation in diatoms.
硅藻是高效的碳捕获生物，它们贡献了全球 20%的碳固定量和 40%的海洋初级生产力，因此它们的生长受到了极大的关注。尽管硅藻具有重要意义，但聚胺（PAs），特别是对各种生物生长至关重要的亚精胺（Spd）的合成机制仍未在硅藻中得到探索。本研究揭示了 Spd 的重要作用，它是通过基于 spermidine synthase（SDS）的途径合成的。在基因组中，PtSDS1 和 PtSDS2 被确认为 SDS 酶，通过酶-底物选择性测定进行验证。它们的不同活性主要由 Y79 活性位点控制。通过单一基因的过表达表明，来自 SDS 合成途径的 PtSDS1、PtSDS2 和 PtSAMDC 都位于细胞质中，对 PA 含量或硅藻生长没有显著影响。PtSDS1 和 PtSAMDC 的共过表达对于提高 Spd 水平至关重要，表明存在多因素调节。升高的 Spd 含量促进硅藻生长，为探索 PA 在硅藻中的功能和调节提供了基础。
