Enhancement of Photophysical and Photosensitizing Properties of Flavin Adenine Dinucleotide by Mutagenesis of the C-Terminal Extension of a Bacterial Flavodoxin Reductase

VALLE, LORENA; ABATEDAGA, INES; MORAN VIEYRA, FAUSTINO EDUARDO; BORTOLOTTI, ANA; CORTEZ, NESTOR; BORSARELLI, CLAUDIO DARIO

Chemphyschem

WILEY-V C H VERLAG GMBH

Lugar: Weinheim; Año: 2015

1439-4235

The role of the mobile C-terminal extension present in Rhodobacter capsulatus NADP(H):ferredoxin reductase (RcFPR) was evaluated by steady-state and dynamic spectroscopies for both intrinsic Trp and FAD in a series of mutants in the absence of NADP(H). Deletion of the six C-terminal amino acids beyond A266 was combined with the replacement A266Y to emulate the structure of plastidic reductases. Our results show that WT RcFPR modification produces subtle global conformational changes, but strongly reduces the local rigidity of the FAD pocket exposing the isoalloxazine ring to the solvent molecules. Thus, the ultrafast charge-transfer quenching of the 1 FAD* by the conserved Tyr66 residue was absent in the mutant series, producing enhancement of the excited singlet and triplet states properties of FAD. This work highlights the delicate balance of specific interactions between FAD and surrounding amino acids modifying the functionality and/or photo-stability of redox flavoproteins.