title: Thermal Isomerization Mechanism in Dronpa and Its Mutants.
abstract: The photoswitching speed of the reversibly switchable fluorescent proteins (RSFPs) from the family of green fluorescent proteins (GFPs) changes upon mutation which is of direct importance for various high-resolution techniques. Dronpa is one of the most used RSFPs. Its point mutants rsFastLime (Dronpa V157G) and rsKame (Dronpa V157L) exhibit a striking difference in their photoswitching speed. Here the QM/MM on-the-fly string method is used in order to explore the details of the thermal isomerization mechanism. The four principal ways in which isomerization may occur have been scrutinized for each of the three proteins. It has been shown that thermal isomerization occurs via a one-bond-flip mechanism in all three proteins, although, in rsKame, where the chromophore is constrained more, the activation free energy difference between hula-twist and one-bond-flip is significantly smaller. Functional mode analysis has been applied to examine the motions of the amino acids during the isomerization. It clearly identifies the importance of Val/Leu 157 as well as the amino acids in the α-helix during the isomerization.
authors.affiliation: Quantum Chemistry and Physical Chemistry Division, Department of Chemistry, KU Leuven , Celestijnenlaan 200F, 3001 Heverlee, Belgium.
authors.forename: Daryna
authors.identifier: 0000-0002-4530-2470
authors.initials: D
authors.lastname: Smyrnova
authors.affiliation: Departament de Química Física, Universitat de València , 46100 Burjassot, Spain.
authors.forename: Kirill
authors.initials: K
authors.lastname: Zinovjev
authors.affiliation: Departament de Química Física, Universitat de València , 46100 Burjassot, Spain.
authors.forename: Iñaki
authors.initials: I
authors.lastname: Tuñón
authors.affiliation: Quantum Chemistry and Physical Chemistry Division, Department of Chemistry, KU Leuven , Celestijnenlaan 200F, 3001 Heverlee, Belgium.
authors.forename: Arnout
authors.initials: A
authors.lastname: Ceulemans
mesh_terms: D005998:Glycine / Q000737:chemistry* / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000737:chemistry* / Q000378:metabolism; D007536:Isomerism; D007700:Kinetics; D007930:Leucine / Q000737:chemistry* / Q000378:metabolism; D056004:Molecular Dynamics Simulation; D017354:Point Mutation; D000072756:Protein Conformation, alpha-Helical; D013696:Temperature; D013816:Thermodynamics; D014633:Valine / Q000737:chemistry* / Q000378:metabolism
chemical_list: D049452:Green Fluorescent Proteins; D007930:Leucine; D014633:Valine; D005998:Glycine