Download MendeleyDual-Cys bacteriophytochromes: intermediates in cyanobacterial phytochrome evolution?
Yang, H.W., Song, J.Y., Song, J.J., Kim, Y.W., Rockwell, N.C., Kim, W., Kim, H., Lagarias, J.C., Park, Y.I.(2025) FEBS J 292: 1197-1216
- PubMed: 39801362
- DOI: https://doi.org/10.1111/febs.17395
- Primary Citation of Related Structures:
9JRY - PubMed Abstract:
Previous studies have identified three families of knotted phytochrome photoreceptors in cyanobacteria. We describe a fourth type: 'hybrid' phytochromes with putative bilin-binding cysteine residues in both their N-terminal 'knot' extensions and cGMP-phosphodiesterase/adenylate cyclase/FhlA (GAF) domains, which we designate as dual-cysteine bacteriophytochromes (DCBs). Recombinant expression of DCBs in Escherichia coli yields photoactive phycocyanobilin (PCB) adducts with red/far-red photocycles similar to those of the GAF-Cys-containing cyanobacterial phytochromes (Cph1s). Incorporation of the PCB precursor, biliverdin IXα (BV), gave multiple populations, one of which appears similar to those of cyanobacterial bacteriophytochromes (cBphPs). A crystal structure of FiDCB bound to BV exhibits two thioether linkages between the GAF- and 'PAS-knot'-Cys residues and the C3 1 and C3 2 atoms of BV. When expressed in Synechocystis sp. PCC 6803, DCBs incorporate PCB rather than BV. DCBs can be converted to photoactive cBphP-, Cph1-, and tandem-cysteine cyanobacterial phytochrome (TCCP) analogs by removal and/or addition of a cysteine residue by site-directed mutagenesis. This structural plasticity contrasts with our inability to generate functional photosensor analogs by analogous site-directed mutagenesis of TCCP and Cph1 representatives. Phylogenetic analysis demonstrates that DCBs do not form a monophyletic clade and also suggest that Cph1 and TCCP families independently emerged from different lineages of cBphPs, possibly via DCB intermediates.
- Department of Biological Sciences, Chungnam National University, Daejeon, Korea.
Organizational Affiliation:
