RT Journal Article
SR Electronic
T1 A phylogenetically diverse class of “blind” type 1 opsins
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 033027
DO 10.1101/033027
A1 Erin A. Becker
A1 Andrew I. Yao
A1 Phillip M. Seitzer
A1 Tobias Kind
A1 Ting Wang
A1 Rich Eigenheer
A1 Katie S. Y. Shao
A1 Vladimir Yarov-Yarovoy
A1 Marc T. Facciotti
YR 2015
UL http://biorxiv.org/content/early/2015/11/26/033027.abstract
AB Opsins are photosensitive proteins catalyzing light-dependent processes across the tree of life. For both microbial (type 1) and metazoan (type 2) opsins, photosensing depends upon covalent interaction between a retinal chromophore and a conserved lysine residue. Despite recent discoveries of potential opsin homologs lacking this residue, phylogenetic dispersal and functional significance of these abnormal sequences have not yet been investigated. We report discovery of a large group of putatively non-retinal binding opsins, present in a number of fungal and microbial genomes and comprising nearly 30% of opsins in the Halobacteriacea, a model clade for opsin photobiology. Based on phylogenetic analyses, structural modeling, genomic context and biochemistry, we propose that these abnormal opsin homologs represent a novel family of sensory opsins which may be involved in taxis response to one or more non-light stimuli. This finding challenges current understanding of microbial opsins as a light-specific sensory family, and provides a potential analogy with the highly diverse signaling capabilities of the eukaryotic G-protein coupled receptors (GPCRs), of which metazoan type 2 opsins are a light-specific sub-clade.