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. 2016 Oct 7;6(13):2414–2430. doi: 10.7150/thno.15878

Figure 12.

Figure 12

Structure and optical properties of bacteriophytochromes (BphPs). (A) Domain organization of BphP. In BphP, BV is secured in the chromophore-binding pocket of the GAF domain and binds covalently to the conserved cysteine residue in the N-terminus of the PAS domain. The chromophore binding module (PAS and GAF domains) can easily be engineered into NIR FPs. PCM: photosensory core module. OTD: output transducing domain. (B) Absorbance spectra of a typical NIR BphP. (C) Conversion between the Pfr state and the Pr state and vice versa is induced by far-red or red light, respectively, owing to trans-cis photoisomerization of the D-ring of the BV chromophore around the C15=C16 double bond (blue arrows). In the dark, the photoconverted state spontaneously reverts back to the ground state (dashed arrows).