Absorption and fluorescence spectroscopic characterization of cryptochrome 3 from Arabidopsis thaliana

The Signaling State of Arabidopsis Cryptochrome 2 Contains Flavin Semiquinone

“…In analogy to the structurally related DNA-photolyase enzymes, it was hypothesized that cryptochromes could also use the fully reduced FAD cofactor for signaling either through intramolecular electron transfer inducing conformational changes within the protein moiety of the photoreceptor or by transfer of an electron to a substrate or signaling partner (4,7,9). Indeed, irradiation of V. cholerae Cry1 and Arabidopsis Cry3 with blue light leads to the accumulation of fully reduced flavin in vitro (10,11). However, V. cholerae Cry1 and Arabidopsis Cry3 belong to a separate cryptochrome group, the CryDASH subfamily (which was shown most recently to have photolyase activity for single-stranded DNA (12)), and has evolved independently from the previously identified plant and animal cryptochromes (36).…”

“…Because of their high sequence and structural similarity (3)(4)(5)(6) and identical flavin cofactor content as DNA-photolyase (7,8), it was hypothesized that cryptochromes might use the same mechanism for signaling as does photolyase for catalysis, which is light-driven electron transfer from the fully reduced flavin FADH Ϫ (2,4,(7)(8)(9). Indeed, spectroscopic studies on Vibrio cholerae Cry1 (10) and Arabidopsis Cry3 (11) have shown that blue light illumination results in the formation of fully reduced flavin similar to the photoactivation process of DNA-photolyase (2). However, CryDASH members were recently shown to have photolyase activity for cyclobutane pyrimidine dimers in single-stranded DNA (12), which is absent for other members of the cryptochrome/photolyase family.…”

Light Signaling, Root Development, and Plasticity

“…1), and CRY1 and CRY2 inhibit root growth via modulation of free auxin levels and polar auxin transport (Mo et al, 2015). The biological function of CRY3 is yet unclear (Song et al, 2006;Klar et al, 2007;Mo et al, 2015). CRYs are nuclear flavoproteins, composed of two domains, an N-terminal photolyase-related region and a C-terminal domain of varying size.…”

Light based cellular interactions: hypotheses and perspectives

“…-The LOV domain generally responds to blue-light ∼450 nm [69]. -The Cryptochrome CRY has two chromophores: pterin which absorbs at a wavelength of 380 nm and flavin at 450 nm [70,71]. -But flavins can have different oxidation states (the fully oxidized state, the semiquinone, a one electron reduced form and the hydroquinone, a two-electron reduced form).…”

“…The fully oxidized absorption spectra are around 446, 370, and 265 nm. The semiquinone state absorbs around 650 nm and the hydroquinone species can absorb light in the UVB range [70].…”