Unprecedented pathway of reducing equivalents in a diflavin-linked disulfide oxidoreductase
|Author||Buey, Rubén M.
Arellano, Juan B.
López Maury, Luis
Galindo Trigo, Sergio
Velázquez Campoy, Adrián
Revuelta, José Luis
Pereda, José M. de
Florencio Bellido, Francisco Javier
Buchanan, Bob B.
|Department||Universidad de Sevilla. Departamento de Bioquímica Vegetal y Biología Molecular|
|Published in||Proceedings of the National Academy of Sciences, 114 (48), 12725-12730.|
|Abstract||Flavoproteinsparticipateinawidevarietyofphysiologicallyrelevant processes that typically involve redox reactions. Within this protein superfamily, there exists a group that is able to transfer reducing equivalents from FAD ...
Flavoproteinsparticipateinawidevarietyofphysiologicallyrelevant processes that typically involve redox reactions. Within this protein superfamily, there exists a group that is able to transfer reducing equivalents from FAD to a redox-active disulfide bridge, which further reduces disulfide bridges in target proteins to regulate their structure and function. We have identified a previously undescribed type of flavin enzyme that is exclusive to oxygenic photosynthetic prokaryotes and that is based on the primary sequence that had been assigned as an NADPH-dependent thioredoxin reductase (NTR). However, our experimental data show that the protein does not transfer reducing equivalents from flavins to disulfides as in NTRs but functions in the opposite direction. High-resolution structures of the protein from Gloeobacter violaceus and Synechocystis sp. PCC6803 obtained by X-ray crystallography showed two juxtaposed FADmoleculespermonomerinredoxcommunicationwithanactive disulfide bridge in a variant of the fold adopted by NTRs. We have tentatively named the flavoprotein “DDOR” (diflavin-linked disulfide oxidoreductase) and propose that its activity is linked to a thiol-basedtransferofreducingequivalentsinbacterialmembranes. These findings expand the structural and mechanistic repertoire of flavoenzymes with oxidoreductase activity and pave the way to explore new protein engineering approaches aimed at designing redox-active proteins for diverse biotechnological applications.
|Citation||Buey, R.M., Arellano, J.B., López Maury, L., Galindo Trigo, S., Velázquez Campoy, A., Revuelta, J.L.,...,Balsera, M. (2017). Unprecedented pathway of reducing equivalents in a diflavin-linked disulfide oxidoreductase. Proceedings of the National Academy of Sciences, 114 (48), 12725-12730.|