Fig. 6: Structural dynamics of the AsLOV2 photocycle revealed by TRXL study.

The photocycle of AsLOV2 includes the G state, three intermediates (I1, I2, and P), and related time constants (WT: 682 μs and 10.6 ms, and I427V: 130 μs and 3.4 ms), as determined from the kinetic analysis of the scattering data. For the TRXL measurements of WT and I427V samples, each sample (WT or I427V) was prepared at a concentration of 1.5 mM in 20 mM Tris pH 7.0, 200 mM NaCl buffer. The optimal structure of G was determined from the structural analysis on the static solution scattering data, while the optimal structures of three intermediates were extracted through the structural analysis using the TRXL data. The optimal structures (I1 and I2) indicate that the structural changes within the A’α and Jα helices allow the exposure of the β-scaffold to the external environment. Subsequently, AsLOV2 undergoes dimerization (P), utilizing the dimeric interface formed between their β-scaffolds. For each state, the optimal structure is depicted alongside the 9 best structures, with the optimal structure highlighted and the remaining structures shown semi-transparently. The A’α and Jα helices are marked in red and blue, respectively, and the remaining structures are marked in gray.