RRC ID 70489
Author Rockwell NC, Moreno MV, Martin SS, Lagarias JC.
Title Protein-chromophore interactions controlling photoisomerization in red/green cyanobacteriochromes.
Journal Photochem Photobiol Sci
Abstract Photoreceptors in the phytochrome superfamily use 15,16-photoisomerization of a linear tetrapyrrole (bilin) chromophore to photoconvert between two states with distinct spectral and biochemical properties. Canonical phytochromes include master regulators of plant growth and development in which light signals trigger interconversion between a red-absorbing 15Z dark-adapted state and a metastable, far-red-absorbing 15E photoproduct state. Distantly related cyanobacteriochromes (CBCRs) carry out a diverse range of photoregulatory functions in cyanobacteria and exhibit considerable spectral diversity. One widespread CBCR subfamily typically exhibits a red-absorbing 15Z dark-adapted state similar to that of phytochrome that gives rise to a distinct green-absorbing 15E photoproduct. This red/green CBCR subfamily also includes red-inactive examples that fail to undergo photoconversion, providing an opportunity to study protein-chromophore interactions that either promote photoisomerization or block it. In this work, we identified a conserved lineage of red-inactive CBCRs. This enabled us to identify three substitutions sufficient to block photoisomerization in photoactive red/green CBCRs. The resulting red-inactive variants faithfully replicated the fluorescence and circular dichroism properties of naturally occurring examples. Converse substitutions restored photoconversion in naturally red-inactive CBCRs. This work thus identifies protein-chromophore interactions that control the fate of the excited-state population in red/green cyanobacteriochromes.
Volume 21(4)
Pages 471-491
Published 2022-4-1
DOI 10.1007/s43630-022-00213-3
PII 10.1007/s43630-022-00213-3
PMID 35411484
PMC PMC9609751
MeSH Bacterial Proteins / chemistry Cyanobacteria* / chemistry Photoreceptors, Microbial* / chemistry Phytochrome* / chemistry
IF 2.831
Algae NIES-21