Supplementary Figure 5: Bilin binding modes in DrBphP.
From: Drop-on-demand sample delivery for studying biocatalysts in action at X-ray free-electron lasers
Four representative DrBphP structures were superposed. The positions of Asp207 and Tyr263 of the PSM (green, PDB code 4Q0J) and our room temperature, SFX PAS-GAF structure (yellow, PDB code 5MG0) were highly congruent, and indicate hydrogen bonding between the two residues. The positions of these residues differed from those found in a separate SFX structure collected at LCLS (magenta, PDB code 5L8M)1, and the photochemically compromised Asp207-Ala mutant (cyan, PDB code 4Q0I), which both show an outward splay of the Tyr263 side chain from residue 207, and absence of hydrogen bonding (e.g., a 3.9 Å inter-residue distance for 5L8M). The D-ring of our PAS-GAF structure appears to be in a position between that found for the PSM and the Asp207-Ala mutant. Pyrrole rings A and D are indicated.
1. Edlund, P. et al. The room temperature crystal structure of a bacterial phytochrome determined by serial femtosecond crystallography. Sci. Rep. 6, 35279 (2016).
