Biosynthesis of Guanitoxin Enables Global Environmental Detection in Freshwater Cyanobacteria.

Harmful cyanobacterial blooms (cyanoHABs) cause recurrent toxic events in global watersheds. Although public health agencies monitor the causal toxins of most cyanoHABs and scientists in the field continue developing precise detection and prediction tools, the potent anticholinesterase neurotoxin, guanitoxin, is not presently environmentally monitored. This is largely due to its incompatibility with widely employed analytical methods and instability in the environment, despite guanitoxin being among the most lethal cyanotoxins. Here, we describe the guanitoxin biosynthesis gene cluster and its rigorously characterized nine-step metabolic pathway from l-arginine in the cyanobacterium Sphaerospermopsis torques-reginae ITEP-024. Through environmental sequencing data sets, guanitoxin (gnt) biosynthetic genes are repeatedly detected and expressed in municipal freshwater bodies that have undergone past toxic events. Knowledge of the genetic basis of guanitoxin biosynthesis now allows for environmental, biosynthetic gene monitoring to establish the global scope of this neurotoxic organophosphate.

有害蓝藻水华（cyanoHABs）在全球水域引发反复的有毒事件。尽管公共卫生机构监测大多数蓝藻水华的致病毒素，该领域的科学家也在不断开发精确的检测和预测工具，但强效抗胆碱酯酶神经毒素——类志贺毒素（guanitoxin）目前尚未受到环境监测。这主要是因为它与广泛使用的分析方法不兼容以及在环境中不稳定，尽管类志贺毒素是最致命的蓝藻毒素之一。在此，我们描述了类志贺毒素生物合成基因簇及其在水华束丝藻（Sphaerospermopsis torques - reginae）ITEP - 024中从L - 精氨酸开始的经过严格表征的九步代谢途径。通过环境测序数据集，类志贺毒素（gnt）生物合成基因在曾经发生过有毒事件的城市淡水水体中被反复检测到并表达。对类志贺毒素生物合成遗传基础的了解现在使得能够通过环境生物合成基因监测来确定这种神经毒性有机磷的全球范围。