In vitro and in vivo characterization of Arabidopsis thaliana (L.) Heynh cryptochrome 2 (cry2) 1404F photoreceptor and the effects of metabolite binding on its structure and photobiocemical properties
2018
Araguirang, G.E.
Plant cryptochromes are blue-light photoreceptors involved in multiple signalling pathways and various photomorphogenic responses such as de-etiolation and regulation of flowering time. One biologically hyperactive mutant of a plant cryptochrome that was previously characterized is cry1L407F (Exner et al., 2010). Protein sequence alignments of different cryptochromes revealed that L407 in cry1 corresponds to I404 in cry2. Point mutation of Ile arrow right Phe in cry2 in this position created a novel mutant. This study provided a baseline data on the elucidation of the properties of cry2404F. Results showed that ATP binding triggered conformational changes, as photoreduction of cry2I404F in vitro. In contrast to previous studies, ATP did not delay dark recovery of the protein but interestingly enhanced the conversion of reduced FAD species to oxidized states upon dark incubation. In vivo, cry2I404F exhibited cop phenotype in the dark and hypersensitivity to various light conditions compared to cry2WT and cry2 mutants. Overall, these data suggest that the hypersensitivity to red and blue light and hyperactivity of this novel mutant in the absence of light can be mostly accounted to structural alterations brought forth by Ile arrow right Phe mutation. Hence, it is necessary to crystallize the structure of this cry2I404F mutant to elucidate the exact mechanism behind its biological hyperactivity.
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