Evolutionary conserved multifunctional nitric oxide synthesis proteins responding to bacterial MAMPs are located at the endoplasmic reticulum

Most Eukaryotic organisms produce nitric oxide (NO); however, the mechanisms underpinning NO’s biosynthesis are only known in animals. In animals, there seems to be a non-described additional system for producing NO in many cell types, including blood vessels where NO is essential for blood pressure control. NO is known to be a signalling molecule of the innate immunity system in plants and fungi although no NO generation has yet been described. In the plant pathogenic fungus Fusarium graminearum, we demonstrate an extra NO-producing system in fungi that seems also present in mammals and plants and, thus, likely the evolutionary original. The discovered NO-producing enzymes are already well-known sterol-producing enzymes with more than one function. Both these enzymes are targets for statins and the major fungicides; thus, the NO production of the new system has consequences for agriculture (pathogen resistance and control) and medicine (blood pressure control, immunity and sepsis).