Dual-Cys bacteriophytochromes: intermediates in cyanobacterial phytochrome evolution?

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 exhibit

SUBMITTER: Yang HW 

PROVIDER: S-EPMC11880981 | biostudies-literature | 2025 Mar

REPOSITORIES: biostudies-literature