Cyanobacteriochrome

Cyanobacteriochromes are phytochrome-related photoreceptor proteins found only in the cyanobacteria. ^[1]

Molecular characterization

Cyanobacteriochrome covalently binds a linear tetrapyrrole molecule in the GAF domain. The A-ring of linear tetrapyrrole molecule is anchored at cysteine residue in the GAF domain via thioethel bond. The GAF domain of cyanobacteriochrome is related to phytochrome GAF, however, These GAF domains are distinct. A second cysteine linkage to the tetrapyrrole is found in some cyanobacteriochrome GAF domains resulting in blue-green photo reversible light sensitivity^[2]

Spectral properties

They perform reversible photoconversion between green(~530 nm)- and red-(~660 nm) absorbing forms or between blue(~430 nm)- and green-absorbing forms. These spectral properties significantly differ from that of phytochrome which photoconverts between red- and far-red(~700 nm)-absorbing forms.

References