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. 2010 Jun 22;20(12):R504-7.
doi: 10.1016/j.cub.2010.04.014.

Phytochromes

Peter H Quail  1
Affiliations

Phytochromes

Peter H Quail. Curr Biol. .
No abstract available

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Figures

Figure 1
Figure 1. Phytochrome (phy) domain structure and intracellular signaling pathway
(A) phy domain structure. Higher plant phy polypeptides, represented by phyB (top), contain two major structural domains (amino- and carboxy-terminal) and several subdomains (N (non-conserved amino-terminal extension), PAS (PER, ARNT, SIM), GAF (cGMP-specific phosphodiesterase, adenylate cyclase, FhlA), PHY (phytochrome) and HKRD (His-kinase related domain)) within each. Small partitioned box above GAF represents the chromophore. Microbial phys, represented by bacteriophytochrome (BphP), have a similar overall architecture but lack the twin caboxy-terminal PAS subdomains. (B) Plant phy photoperception and signal transduction in regulating seedling photomorphogenesis. phy molecules switch reversibly between their Pr and Pfr conformers upon sequential absorption of red (R) and (FR) photons. Pfr formation (signal perception) triggers rapid translocation into the nucleus where the activated molecule interacts with bHLH-class, phy-interacting transcription factors (PIFs), such as PIF3, initiating alterations in gene expression, via a transcriptional network, that culminates in the switch from skotomorphogenesis to photomorphogenesis (seedling de-etiolation). About 10% (2,400) of the genes in the Arabidopsis genome display altered expression within 24 h of first exposure to R light, whereas 1% (250 genes) change expression within 1 h of initial exposure (‘early-response’ genes). (C) The dark side: multiple PIF bHLH factors repress photomorphogenesis in darkness. A quadruple pif1 pif3 pif4 pif5 (pifq) mutant of Arabidopsis displays a constitutively photomorphogenic (cop)-like phenotype in completely dark-grown seedlings. (Figure coutesy of B. Al-Sady, P. Leivar, E. Monte and J. Tepperman.)
See this image and copyright information in PMC

References

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