Fig. 2: Excitation-energy transfer from Wd to Wp and Wc in UVR8.
From: A leap in quantum efficiency through light harvesting in photoreceptor UVR8
a Fluorescence transients for mono-6Wd gated at 320, 325, and 330 nm. Note the log scale starting from 2 ns. The lifetimes of Wd were determined to be τ1 = 0.5 ns (29%) and τ2 = 2.7 ns (71%). b–f Timescales from a global fitting and lifetime-associated spectra of selected 6Wd + 1Wp (b), 6Wd + 2Wp (c), 6Wd + 3Wp (d), 6Wd + 4Wc (e), and WT (f). Fluorescence transients are shown in Supplementary Fig. 1. For each panel, the solid lines are the steady-state emission spectra of various mutants. The lifetime-associated spectra are shown in various symbols and the directly measured spectra are shown in lines. The time constant corresponding to the original 2.7-ns component is highlighted in a box. 6Wd1 and 6Wd2 are the emission spectra of the two Wd lifetimes decomposed as described in Methods. Note that the total spectrum of 1.4 and 5.4 ns shown for 6Wd + 4Wc agrees with the 4Wc emission. The total spectrum of 1.4 and 5.5 ns shown for WT can be decomposed into 3Wp and 4Wc emission (dashed lines). g Energy-transfer rate distributions for each Wd to 3Wp (top) and to 4Wc (bottom) based on QM/MM methods. h–j Simulations of the original 2.7-ns component decay dynamics of 6Wd for 6Wd + 3Wp (h), 6Wd + 4Wc (i), and WT (j) based on RET rate distributions. For each case, the overall 6Wd decay curve (black line), the sum of six individual Wd decay curves (dashed lines), can be fitted with a single-exponential decay and agrees well with the experimental decay dynamics shown in (d–f). k The 168 possible energy-transfer pathways (based on QM/MM) from all Wd to 14 interfacial W residues (3Wp + 4Wc on both subunits). The total RET time constants based on QM/MM (blue) and on X-ray structure (red) are shown near each Wd. Each line represents one energy-transfer pathway. Colors of the lines are based on effective RET time constants. The dominant paths are shown in red.
