| Type: | Family | Name: | Bacteriophytochrome, CheY-like |
| Description: | This entry contains bacteriophytochromes, or BphPs (light-regulated signal transduction histidine kinases) with the receiver (CheY-like) domain fused at the C terminus.Phytochrome dimeric photoreceptors regulate growth and development by sensing ambient light []. Apart from phytochromes in photosynthetic organisms, phytochrome-like photoreceptors have been found in several nonphotosynthetic organisms, including in the heterotrophic eubacteria Deinococcus radioduransand Pseudomonas aeruginosa, ]. These homodimeric photoreceptors sense red light (R) and far-red light (FR) through photointerconversion between two stable conformations, a R-absorbing Pr form and a FR-absorbing Pfr form [].Phytochromes in general contain a signature N-terminal chromophore-binding region (CBD) that includes GAF and PHY domains, both of which are essential for autocatalytically binding bilin chromophores. A C-terminal module is involved in signal transduction and homodimerisation, and is different in different groups of phytochromes. Phytochromes are divided into three groups: plant phys, cyanobacterial phys (Cphs), and bacteriophytochrome photoreceptors (BphPs) [].The BphPs are common among photosynthetic and nonphotosynthetic Eubacteria and present in some fungi []. They act as photoregulated kinases that presumably initiate the phosphorelay cascade by phosphotransfer to an associated response regulator (RR). In some cases, the receiver (CheY-like) domain of this RR is fused to the C-terminal end of the BphP (such hybrid proteins are in this entry).Like Cphs, BphPs often contain the canonical two-component histidine kinase motif and act as histidine kinases in vitro. The main distinction is that they use the bilin biliverdin (BV) as the chromophore []. Included in the CBD are the positionally conserved cysteine (Cys-20 and Cys-13) and histidine (His-250 and His-248) residues that could serve as the chromophore-binding site, by using either a thiolether or Schiff-base-type linkage, respectively [, , , ]. | Short Name: | Bactrphtchr_CheY |
