Species Widely Distributed in Halophilic Archaea Exhibit Opsin-Mediated Inhibition of Bacterioruberin Biosynthesis

Abstract

All organisms use a variety of mechanisms to allocate limited resources to match their needs in their current environment. Here, we explore how halophilic microbes use a novel mechanism to allow efficient production of rhodopsin, a complex of an opsin protein and a retinal prosthetic group. We previously demonstrated that Halobacterium salinarum bacterioopsin directs available resources toward retinal by inhibiting synthesis of bacterioruberin, a molecule that shares precursors with retinal. In this work, we show that this mechanism can be carried out by proteins from halophilic Archaea that are not closely related to H. salinarum and those in at least one species of Bacteria . Therefore, opsin-mediated inhibition of bacterioruberin synthesis may be a highly conserved, ancient regulatory mechanism.