Institute for Marine and Environmental Technologies, University of Maryland Center for Environmental Science, 701 East Pratt St., Baltimore, MD 21202, USA.
University of Maryland School of Medicine, 655 W. Baltimore Street, Baltimore, MD 21201, USA.
Mar Drugs. 2023 Jul 27;21(8):425. doi: 10.3390/md21080425.
Dinoflagellates are unicellular organisms that are implicated in harmful algal blooms (HABs) caused by potent toxins that are produced through polyketide synthase (PKS) pathways. However, the exact mechanisms of toxin synthesis are unknown due to a lack of genomic segregation of fat, toxins, and other PKS-based pathways. To better understand the underlying mechanisms, the actions and expression of the PKS proteins were investigated using the toxic dinoflagellate as a model. Cerulenin, a known ketosynthase inhibitor, was shown to reduce acetate incorporation into all fat classes with the toxins amphidinol and sulpho-amphidinol. The mass spectrometry analysis of cerulenin-reacted synthetic peptides derived from ketosynthase domains of multimodular PKS transcripts demonstrated a strong covalent bond that could be localized using collision-induced dissociation. One multi-modular PKS sequence present in all dinoflagellates surveyed to date was found to lack an AT domain in toxin-producing species, indicating -acting domains, and was shown by Western blotting to be post-transcriptionally processed. These results demonstrate how toxin synthesis in dinoflagellates can be differentiated from fat synthesis despite common underlying pathway.
甲藻是单细胞生物，它们与通过聚酮合酶（PKS）途径产生的强效毒素有关，这些毒素导致有害藻类大量繁殖（HABs）。然而，由于脂肪、毒素和其他基于 PKS 的途径缺乏基因组分离，因此毒素合成的确切机制尚不清楚。为了更好地了解潜在的机制，使用有毒甲藻作为模型研究了 PKS 蛋白的作用和表达。已知的酮合酶抑制剂 Cerulenin 被证明可以减少毒素 Amphidinol 和 Sulpho-amphidinol 中所有脂肪类别的乙酸盐掺入。用 Cerulenin 反应的来自多模块 PKS 转录物的酮合酶结构域的合成肽的质谱分析表明存在强共价键，可以使用碰撞诱导解离进行定位。在迄今为止调查的所有甲藻中，发现一个存在于所有甲藻中的多模块 PKS 序列在产生毒素的物种中缺乏 AT 结构域，表明存在-作用结构域，并通过 Western blot 显示其被转录后加工。这些结果表明，尽管存在共同的基础途径，但甲藻中的毒素合成如何与脂肪合成区分开来。
