A novel photoactive GAF domain of cyanobacteriochrome AnPixJ that shows reversible green/red photoconversion.
We report the discovery of a novel cyanobacteriochrome, the green/red photoreceptor AnPixJ (All1069), isolated from the heterocyst-forming cyanobacterium Anabaena (Nostoc) sp. PCC 7120. Cyanobacteriochromes are a recently emerging tetrapyrrole-based photoreceptor superfamily that are distantly related to the conventional red/far-red photoreceptor phytochromes (Phys). The chromophore-binding domains of AnPixJ produced in cyanobacterial and Escherichia coli cells both showed a reversible and full photoconversion between a green-absorbing form (lambda(max)=543 nm) and a red-absorbing form (lambda(max)=648 nm). Denaturation analysis revealed that the green-absorbing form and the red-absorbing form covalently ligated phycocyanobilin with E-configuration and Z-configuration at the C15C16 double bond, respectively. Time-resolved spectral analysis showed the formation of the first intermediate state peaking at 680 nm from the dark-stable red-absorbing form. This step resembles the first photoconversion step from the red-absorbing form to the red-shifted lumi-R intermediate state of the Phys. These results suggest that the Pr of AnPixJ is almost equivalent to that of the Phys and starts a primary photoreaction with Z-to-E isomerization in a mechanism similar to that in the Phys, but is finally photoconverted to the unique green-absorbing form.
Department of Life Sciences Biology, Graduate School of Art and Sciences, University of Tokyo, Komaba, Meguro, Tokyo 153-0041, Japan.
Rei
R
Narikawa
Yoshimasa
Y
Fukushima
Takami
T
Ishizuka
Shigeru
S
Itoh
Masahiko
M
Ikeuchi
D000409:Alanine / Q000378:metabolism; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D017033:Anabaena / Q000737:chemistry*; D004926:Escherichia coli / Q000235:genetics; D006639:Histidine / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008027:Light; D008969:Molecular Sequence Data; D015394:Molecular Structure; D010786:Photoreceptor Cells / Q000737:chemistry / Q000378:metabolism* / Q000528:radiation effects; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D052980:Phycobilins / Q000378:metabolism; D010798:Phycocyanin / Q000378:metabolism; D010834:Phytochrome / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D011489:Protein Denaturation; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D013056:Spectrophotometry, Ultraviolet; D014508:Urea / Q000494:pharmacology
D045322:Photosynthetic Reaction Center Complex Proteins; D052980:Phycobilins; D010798:Phycocyanin; D010834:Phytochrome; C011069:phycocyanobilin; D006639:Histidine; D014508:Urea; D000409:Alanine