A Hinge Migration Mechanism Unlocks the Evolution of Green-to-Red Photoconversion in GFP-Like Proteins
In proteins, functional divergence involves mutations that modify structure and dynamics. Here we provide experimental evidence for an evolutionary mechanism driven solely by long-range dynamic motions without significant backbone adjustments, catalytic group rearrangements, or changes in subunit assembly. Crystallographic structures were determined for several reconstructed ancestral proteins belonging to a GFP class frequently employed in superresolution microscopy. Their chain flexibility was analyzed using molecular dynamics and perturbation response scanning. The green-to-red photoconvertible phenotype appears to have arisen from a common green ancestor by migration of a knob-like anchoring region away from the active site diagonally across the β barrel fold. The allosterically coupled mutational sites provide active site conformational mobility via epistasis. We propose that light-induced chromophore twisting is enhanced in a reverse-protonated subpopulation, activating internal acid-base chemistry and backbone cleavage to enlarge the chromophore. Dynamics-driven hinge migration may represent a more general platform for the evolution of novel enzyme activities.
- Author (aut): Kim, Hanseong
- Author (aut): Zou, Taisong
- Author (aut): Modi, Chintan
- Author (aut): Dorner, Katerina
- Author (aut): Grunkemeyer, Timothy
- Author (aut): Chen, Liqing
- Author (aut): Fromme, Raimund
- Author (aut): Matz, Mikhail V.
- Author (aut): Ozkan, Sefika
- Author (aut): Wachter, Rebekka
- Contributor (ctb): Department of Chemistry and Biochemistry