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Data from: Protein-Chromophore interactions controlling photoisomerization in red/green cyanobacteriochromes

Data files

Apr 07, 2022 version files 386.53 KB

Abstract

Cyanobacteriochromes (CBCRs) are cyanobacterial photoreceptors distantly related to the phytochromes found in a broad range of bacteria, algae, and plants. CBCRs can control several aspects of cyanobacterial photobiology, including phototaxis, motile/sessile transitions, and complementary chromatic acclimation. CBCRs can sense a very broad range of light, with different subfamilies detecting UV, violet, blue, teal, green, yellow, orange, red, or far-red light (375-745 nm). This dataset is associated with a study of red/green CBCRs, a group in which red-absorbing dark states give rise to green-absorbing photoproducts upon light absorption and subsequent 15,16-photoisomerization of the phycocyanobilin chromophore. Interestingly, some members of this group fail to undergo this reaction. By comparing a conserved lineage of these red-inactive CBCRs to their photoactive red/green relatives, we identified three residues that determine whether photoisomerization can occur: introduction of these three substitutions is sufficient to block photoisomerization in a red/green CBCR or restore it in a red-inactive one. Such engineered red-inactive ones also mimic other properties of naturally occuring red-inactive CBCRs. This study thus demonstrates that it is possible to engineer the fate of the excited-state population of a biological photoreceptor with only a few amino acid substitutions.

This work used maximum likelihood phylogenetic analysis to identify a conserved lineage of red-inactive CBCRs. Chosen proteins were then obtained through commercial gene synthesis and recombinantly expressed in E. coli cells that had been engineered to product phycocaynobilin or other bilin chromophores. Purified proteins were then characterized using absorption, fluorescence, and circular dichroism (CD) spectroscopy. This dataset provides raw data for that analysis. Data are ogranized as a single gzipped tarball with an associated README file. Within the compressed archive, there are five subdirectories containing files for phylogenetic analysis, for absorption spectroscopy, for fluorescence spectroscopy, for CD spectroscopy, and for the sequences of the synthetic genes. Phylogenetic files are in CLUSTAL, PHYLIP, and Newick format (starting alignment in CLUSTAL format; input file for phylogenetic inference, PHYLIP format; output tree, Newick format). Spectroscopic data are in .csv or tab-delimited flat text. Synthetic gene sequences are in FASTA format.