Nitric oxide synthases from photosynthetic microorganisms: discovering the tip of the iceberg

Abstract

Nitric oxide (NO) is a signal molecule produced in species of all kingdoms of life. In animals, NO is synthesized by NO synthases (NOSs) enzymes using l-arginine as substrate. In the plant kingdom, findings showed the presence of NOS in several algal species but none in land plants. In recent years, a singular NOS from cyanobacteria was characterized with a globin domain in the N-terminus. Transgenic plants expressing the microalgal and cyanobacterial NOSs showed gain of functions. Here we will discuss the key features of NOS expressed in photosynthetic organisms and we will reinforce the idea of a novel role for NOS, associated to nitrogen metabolism in higher plants.