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Figure 1.
Fig. 1. VVD structure. (A) Crystallographic dimer of VVD-36,
including the PAS core (blue), N-terminal cap (yellow), and FAD
insertion loop (red). The N terminus, resolved only in the left
molecule, projects toward the solvent-exposed FAD adenosine
moiety (orange). (B) Superposition of the PAS domains of VVD
(green), PYP (magenta), Drosophila PER (red), and AsLOV2 domain
(blue). All proteins share a structurally conserved PAS ß
scaffold (yellow) and helical regions (gray) that pack with a
variable helical element possibly involved in signal
transduction. (C) Photocycle of VVD-36 at 25°C. Blue-light
illumination of VVD forms a photoadduct between Cys^108 and the
C4a position of the flavin ring (inset). Adduct formation
bleaches the flavin absorption bands at 428, 450, and 478 nm and
produces a single peak at 390 nm. Recovery proceeds with t[1/2]
= 10^4 s and three isosbestic points at 330, 385, and 413 nm.
Spectra are displayed at 3000 s increments.
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