Light-induced alteration of low-temperature interprotein electron transfer between photosystem I and flavodoxin.
Electron paramagnetic resonance (EPR) was used to study light-induced electron transfer in Photosystem I-flavodoxin complexes. Deuteration of flavodoxin enables the signals of the reduced flavin acceptor and oxidized primary donor, P(700)(+), to be well-resolved at X- and D-band EPR. In dark-adapted samples, photoinitiated interprotein electron transfer does not occur at 5 K. However, for samples prepared in dim light, significant interprotein electron transfer occurs at 5 K and a concomitant loss of the spin-correlated radical pair P(+)A(1A)(-) signal is observed. These results indicate a light-induced reorientation of flavodoxin in the PSI docking site that allows a high quantum yield efficiency for the interprotein electron transfer reaction.
Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, United States. utschig@anl.gov
Lisa M
LM
Utschig
David M
DM
Tiede
Oleg G
OG
Poluektov
D004578:Electron Spin Resonance Spectroscopy; D004579:Electron Transport / Q000528:radiation effects; D005418:Flavodoxin / Q000378:metabolism* / Q000528:radiation effects; D007700:Kinetics; D008027:Light; D010084:Oxidation-Reduction; D010788:Photosynthesis / Q000502:physiology; D045331:Photosystem I Protein Complex / Q000378:metabolism* / Q000528:radiation effects; D010970:Plastocyanin / Q000378:metabolism; D046940:Synechococcus / Q000378:metabolism; D020524:Thylakoids / Q000378:metabolism
D005418:Flavodoxin; D045331:Photosystem I Protein Complex; D010970:Plastocyanin