TY  - JOUR
A1  - Staudt, Heike
A1  - Oesterhelt, Dieter
A1  - Grininger, Martin
A1  - Wachtveitl, Josef
T1  - Ultrafast excited-state deactivation of flavins bound to dodecin
T2  - Journal of biological chemistry
N2  - Dodecins, a group of flavin-binding proteins with a dodecameric quaternary structure, are able to incorporate two flavins within each of their six identical binding pockets building an aromatic tetrade with two tryptophan residues. Dodecin from the archaeal Halobacterium salinarum is a riboflavin storage device. We demonstrate that unwanted side reactions induced by reactive riboflavin species and degradation of riboflavin are avoided by ultrafast depopulation of the reactive excited state of riboflavin. Intriguingly, in this process, the staggered riboflavin dimers do not interact in ground and photoexcited states. Rather, within the tetrade assembly, each riboflavin is kept under the control of the respective adjacent tryptophan, which suggests that the stacked arrangement is a matter of optimizing the flavin load. We further identify an electron transfer in combination with a proton transfer as a central element of the effective excited state depopulation mechanism. Structural and functional comparisons of the archaeal dodecin with bacterial homologs reveal diverging evolution. Bacterial dodecins bind the flavin FMN instead of riboflavin and exhibit a clearly different binding pocket design with inverse incorporations of flavin dimers. The different adoption of flavin changes photochemical properties, making bacterial dodecin a comparably less efficient quencher of flavins. This supports a functional role different for bacterial and archaeal dodecins.
KW  - Electron Transfer
KW  - Flavin
KW  - Flavoproteins
KW  - Protein Dynamics
KW  - Spectroscopy
KW  - Flavin-binding Protein
KW  - Proton Transfer
KW  - Ultrafast Spectroscopy
Y1  - 2021
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/76665
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-766650
SN  - 0021-9258
VL  - 287
IS  - 21
SP  - 17637
EP  - 17644
PB  - American Society for Biochemistry and Molecular Biology Publications
CY  - Bethesda, Md
ER  -