Photoinduced damage of AsLOV2 domain is accompanied by increased singlet oxygen production due to flavin dissociation.

Flavin mononucleotide (FMN) belongs to the group of very efficient endogenous photosensitizers producing singlet oxygen, O, but with limited ability to be targeted. On the other hand, in genetically-encoded photosensitizers, which can be targeted by means of various tags, the efficiency of FMN to produce O is significantly diminished due to its interactions with surrounding amino acid residues. Recently, an increase of O production yield by FMN buried in a protein matrix was achieved by a decrease of quenching of the cofactor excited states by weakening of the protein-FMN interactions while still forming a complex.

Conformational properties of LOV2 domain and its C450A variant within broad pH region.

LOV2 (Light-Oxygen-Voltage) domain from Avena sativa phototropin 1 (AsLOV2) belongs to the superfamily of PAS (Per-Arnt-Sim) domains, members of which function as signaling sensors. AsLOV2 undergoes a conformational change upon blue-light absorption by its FMN cofactor. AsLOV2 wild type (wt) is intensively studied as a photo-switchable element in conjugation with various proteins.