1] Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan. [2] Japan Science and Technology Agency, CREST, Tokyo, Japan. [3].
Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan.
Nat Chem Biol. 2014 Aug;10(8):648-55. doi: 10.1038/nchembio.1573. Epub 2014 Jun 29.
The Japanese marine sponge Discodermia calyx contains a major cytotoxic compound, calyculin A, which exhibits selective inhibition of protein phosphatases 1 and 2A. It has long been used as a chemical tool to evaluate intracellular signal transduction regulated by reversible protein phosphorylation. We describe the identification of the biosynthetic gene cluster of calyculin A by a metagenome mining approach. Single-cell analysis revealed that the gene cluster originates in the symbiont bacterium 'Candidatus Entotheonella' sp. A phosphotransferase encoded in the gene cluster deactivated calyculin A to produce a newly discovered diphosphate, which was actually the biosynthetic end product. The diphosphate had been previously overlooked because of the enzymatic dephosphorylation that occurred in response to sponge tissue disruption. Our work presents what is to our knowledge the first evidence for the biosynthetic process of calyculin A along with a notable phosphorylation-dephosphorylation mechanism to regulate toxicity, suggesting activated chemical defense in the most primitive of all multicellular animals.
日本海洋海绵 Discodermia calyx 中含有一种主要的细胞毒性化合物 calyculin A，它对蛋白磷酸酶 1 和 2A 具有选择性抑制作用。长期以来，它一直被用作评估受可逆蛋白磷酸化调节的细胞内信号转导的化学工具。我们通过宏基因组挖掘方法鉴定了 calyculin A 的生物合成基因簇。单细胞分析表明，该基因簇起源于共生细菌“Candidatus Entotheonella”sp。基因簇中编码的磷酸转移酶使 calyculin A 失活，产生一种新发现的二磷酸，这实际上是生物合成的终产物。由于海绵组织破裂时发生的酶去磷酸化作用，以前忽略了二磷酸。我们的工作首次提供了 calyculin A 生物合成过程的证据，以及一个显著的磷酸化-去磷酸化机制来调节毒性，这表明在所有多细胞动物中最原始的动物中存在激活的化学防御。
