6tby
Phycocyanobilin-adducted PAS-GAF bidomain of Sorghum bicolor phyB
Structural highlights
FunctionPHYB_SORBI Regulatory photoreceptor which exists in two forms that are reversibly interconvertible by light: the Pr form that absorbs maximally in the red region of the spectrum and the Pfr form that absorbs maximally in the far-red region. Photoconversion of Pr to Pfr induces an array of morphogenic responses, whereas reconversion of Pfr to Pr cancels the induction of those responses. Pfr controls the expression of a number of nuclear genes including those encoding the small subunit of ribulose-bisphosphate carboxylase, chlorophyll A/B binding protein, protochlorophyllide reductase, rRNA, etc. It also controls the expression of its own gene(s) in a negative feedback fashion.[UniProtKB:P14713] Publication Abstract from PubMedPlant phytochromes are red/far-red photochromic photoreceptors that act as master regulators of development, controlling the expression of thousands of genes. Here, we describe the crystal structures of four plant phytochrome sensory modules, three at about 2 A resolution or better, including the first of an A-type phytochrome. Together with extensive spectral data, these structures provide detailed insight into the structure and function of plant phytochromes. In the Pr state, the substitution of phycocyanobilin and phytochromobilin cofactors has no structural effect, nor does the amino-terminal extension play a significant functional role. Our data suggest that the chromophore propionates and especially the phytochrome-specific domain tongue act differently in plant and prokaryotic phytochromes. We find that the photoproduct in period-ARNT-single-minded (PAS)-cGMP-specific phosphodiesterase-adenylyl cyclase-FhlA (GAF) bidomains might represent a novel intermediate between MetaRc and Pfr. We also discuss the possible role of a likely nuclear localization signal specific to and conserved in the phytochrome A lineage. Structural insights into photoactivation and signalling in plant phytochromes.,Nagano S, Guan K, Shenkutie SM, Feiler C, Weiss M, Kraskov A, Buhrke D, Hildebrandt P, Hughes J Nat Plants. 2020 May 4. pii: 10.1038/s41477-020-0638-y. doi:, 10.1038/s41477-020-0638-y. PMID:32366982[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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