Archaeal LOV domains from Lake Diamante: first functional characterization of an halo-adapted photoreceptor

Abstract

Abstract High-Altitude Andean Lakes have been described as polyextremophilic environments and plenty photoinduced processes have been documented. Lake Diamante metagenomic taxonomical analysis revealed mostly members from Archaea domain of life. In this context, we searched for Light Oxygen Voltage photoreceptors where 24 of these Archaeal sequences were part of two major groups (A and B) except for 3 domains that did not group even with the reference sequences included for the analysis. Several signatures of halo-adapted proteins were found amongst archaeal sequences, i.e. abundance of acidic residues on the surface, increased number of arginine residues at the expense of lysines and a multiplicity of salt bridges. Heterologous expression of one of these domains, ALovD-1, showed that the photophysics for the dark and the light adapted states was fairly conserved, but most importantly that is a slow cycling type, and a moderate halophilic photoreceptor since it conserves activity at 0.5 M of monovalent salt. This is the first Archaeal LOV domain characterized in the literature to our knowledge.