Figure 1

Phylogenetic tree of microbial rhodopsins from Archaea and Eubacteria, representing the phylogenetic relationship between Gloeobacter rhodopsin and related proteins. HsBR, bacteriorhodopsin from H. salinarum; HvSRI, HsSRI, SrSRI, sensory rhodopsin I from Haloarcula vallismortis, H. salinarum, and Salinibacter ruber; HsSRII, HvSRII, NpSRII, sensory rhodopsin II from H. salinarum, Haloarcula vallismortis, Natronomonas pharaonis; MrHR, Mastigocladopsis repens halorhodopsin; ASR, Anabaena sensory rhodopsin; NsXeR, Nanosalinarum sp xenorhodopsin; HsHR, NpHR, SrHR, halorhodopsin from H. salinarum, N. pharaonis, and S. ruber; BPR, blue-absorbing proteorhodopsin; GPR, green-absorbing proteorhodopsin; KR2, sodium-pumping rhodopsin from Krokinobacter eikastus; FR, chloride-pumping rhodopsin from Fulvimarina pelagi; TR, thermophilic rhodopsin from Thermus thermophilus; GR, rhodopsin from Gloeobacter violaceus PCC 7421; XR, xanthorhodopsin from S. ruber. The evolutionary history was inferred using the Neighbor-Joining method⁶⁴. The optimal tree with the sum of branch length = 11.29080174 is shown. The tree is drawn to scale, with branch lengths in the same units as those of the evolutionary distances used to infer the phylogenetic tree. The evolutionary distances were computed using the Poisson correction method⁶⁵ and are in the units of the number of amino acid substitutions per site. The analysis involved 23 amino acid sequences. All positions containing gaps and missing data were eliminated. There was a total of 189 positions in the final dataset. Evolutionary analyses were conducted with MEGA7⁶⁶.