Cyanobacteriochrome TePixJ of Thermosynechococcus elongatus harbors phycoviolobilin as a chromophore.
Cyanobacteria have several putative photoreceptors (designated cyanobacteriochromes) that are related to but distinct from the established phytochromes. The GAF domain of the phototaxis regulator, PixJ, from a thermophilic cyanobacterium Thermosynechococcus elongatus BP-1 (TePixJ_GAF) is a cyanobacteriochrome which exhibits reversible photoconversion between a blue light-absorbing form (max = 433 nm) and a green light-absorbing form (max = 531 nm). To study the chromophore, we prepared TePixJ_GAF chromoprotein from heterologously expressed Synechocystis and performed spectral analysis after denaturation by comparing it with the cyanobacterial phytochrome Cph1 which harbors phycocyanobilin (PCB) as a chromophore. The results indicated that the chromophore of TePixJ is not PCB, but its isomer, phycoviolobilin (PVB). It is suggested that the GAF domain of TePixJ has auto-lyase and auto-isomerase activities.
Ishizuka
Takami
T
Department of Life Sciences (Biology), The University of Tokyo, Komaba 3-8-1, Meguro, Tokyo, Japan.
Narikawa
Rei
R
Kohchi
Takayuki
T
Katayama
Mitsunori
M
Ikeuchi
Masahiko
M
D001426:Bacterial Proteins / Q000737:chemistry*; D000458:Cyanobacteria / Q000737:chemistry*; D008027:Light; D020283:Photoreceptors, Microbial / Q000737:chemistry*; D052980:Phycobilins / Q000032:analysis*; D010798:Phycocyanin / Q000032:analysis*; D013057:Spectrum Analysis
D001426:Bacterial Proteins; D020283:Photoreceptors, Microbial; D052980:Phycobilins; C526232:phycoviolobilin; D010798:Phycocyanin; C011069:phycocyanobilin