Evidence of a Light-Sensing Role for Folate in Arabidopsis Cryptochrome Blue-Light Receptors Hoang Nathalie , Bouly Jean-Pierre , Ahmad Margaret Molecular Plant Volume 1, Issue 1, Pages 68-74 (January 2008) DOI: 10.1093/mp/ssm008 Copyright © 2008 The Authors. All rights reserved. Terms and Conditions
Figure 1 Wavelength sensitivity of cry2-dependent proteolysis in vivo. Two-day-old etiolated Arabidopsis seedlings were irradiated with the indicated photon fluence rate (μmol m−2 s−1) of light for 30 min. The level of cry2 protein as compared to dark control seedlings was quantitated from Western blot (see methods) and plotted as a function of photon fluence. Error bars represent SD of three independent measurements. Molecular Plant 2008 1, 68-74DOI: (10.1093/mp/ssm008) Copyright © 2008 The Authors. All rights reserved. Terms and Conditions
Figure 2 Action spectrum of cry2 degradation in Arabidopsis. Photon fluence required to attain 50% protein degradation were determined from the curves in Figure 1. These values are plotted as a function of wavelength to give a representation of wavelength sensitivity of cry2 activation. Molecular Plant 2008 1, 68-74DOI: (10.1093/mp/ssm008) Copyright © 2008 The Authors. All rights reserved. Terms and Conditions
Figure 3 Excitation spectrum of sf9 cells overexpressing Arabidopsis cry1. Emission is at 525 nm to detect the presence of oxidized flavin. (A) Excitation spectrum below 500 nm of whole cells expressing Arabidopsis cry1. (B) Difference excitation spectrum of infected (expressing cry1) minus uninfected (non-expressing) control cell cultures. This plot derives the contribution of cry1 to the excitation spectrum. Molecular Plant 2008 1, 68-74DOI: (10.1093/mp/ssm008) Copyright © 2008 The Authors. All rights reserved. Terms and Conditions
Figure 4 Comparative in-vivo photoreduction of cry1 at 450 and 380 nm. Living cry1-expressing sf9 insect cells were irradiated with either blue (450 nm) or UV/A (380 nm) light at a low photon fluence rate (2 μmol m−2 s−1). Samples were returned briefly at the indicated time points to the fluorimeter for measurement of emission at 525 nm (excitation 450 nm). Molecular Plant 2008 1, 68-74DOI: (10.1093/mp/ssm008) Copyright © 2008 The Authors. All rights reserved. Terms and Conditions
Figure 5 Effect of DHAP on pterin accumulation in sf9 cells. Excitation spectra are shown for emission monitored at 440 nm (peak pterin emission). Cell cultures expressing cry1 were treated (see methods) with differing concentrations of DHAP. Decrease in peak intensity at 380 nm indicates reduced levels of pterin. Molecular Plant 2008 1, 68-74DOI: (10.1093/mp/ssm008) Copyright © 2008 The Authors. All rights reserved. Terms and Conditions
Figure 6 Effect of DHAP on in-vivo photoreduction of cry1 by 450 nm light. Living cry1-expressing insect cells were irradiated with medium-intensity blue light (10 μmol m−2 s−1) over time. Samples were returned briefly at the indicated time points to the fluorimeter for measurement of emission at 525 nm (excitation 450 nm). A parallel sample was treated with 5 mM DHAP and analyzed under the same conditions. The plot represents a decrease in oxidized flavin (a measure of cry1 activation) over time in response to blue-light irradiation. Molecular Plant 2008 1, 68-74DOI: (10.1093/mp/ssm008) Copyright © 2008 The Authors. All rights reserved. Terms and Conditions
Figure 7 Effect of DHAP on in-vivo photoreduction of cry1 by 380 nm light. Living cry1-expressing insect cells were irradiated with UV/A light (2 μmol m−2 s−1). Samples were returned briefly at the indicated time points to the fluorimeter for measurement of emission at 525 nm (excitation 450 nm). A parallel sample was treated with 5 mM DHAP and analyzed under the same conditions. The plot represents a decrease in oxidized flavin (a measure of cry1 activation) over time in response to UV/A light irradiation. Molecular Plant 2008 1, 68-74DOI: (10.1093/mp/ssm008) Copyright © 2008 The Authors. All rights reserved. Terms and Conditions