Role of the interface between the FMN and FAD domains in the control of redox potential and electronic transfer of NADPH-cytochrome P450 reductase
Résumé
NADPH cytochrome P450 reductase (CPR) is a multidomain protein containing two flavin-containing domains joined by a connecting domain supposed to control the necessary movements of the catalytic domains during electronic cycles. We present a detailed biochemical analysis of two chimeric CPR composed of the association of human or yeast FMN with the alternate connecting/FAD domains. Despite the assembly of domains having relatively large evolutionary distance between them, our data support the idea that the integrity of the catalytic cycle is conserved in our chimeric enzymes while the recognition, interactions and positioning of both catalytic domains are probably modified. The main consequences of the chimerogenesis are a decrease of the internal electron transfer rate between both flavins correlated with changes in the geometry of chimeric CPR in solution. Results presented herein highlight the role of the linker and connecting domain in the recognition at the interfaces between the catalytic domains and the impact of interdomain interactions on the redox potentials of the flavins, the internal electron transfer efficiency and the global conformation and dynamical equilibrium of the CPR.
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