Figure 7: Evidence of electron transfer from QA°− to DMBQ in the psbT mutant strains. | Nature Communications

Figure 7: Evidence of electron transfer from QA° to DMBQ in the psbT mutant strains.

From: Redesigning the QA binding site of Photosystem II allows reduction of exogenous quinones

Figure 7

(a) Direct electron transfer from QA° to DMBQ as revealed by chlorophyll fluorescence analysis under dim light in the psbT mutant strains. The ratio of (FMFS)/FM normalized to the level in the absence of DMBQ was measured in the presence of 10 μM DCMU at actinic light of 0.6 μmol photons m−2 s−1. The larger normalized (FMFS)/FM ratio in these mutant strains relative to the aadA control strain suggests that additional electron transfer from QA° to DMBQ competes with fluorescence. Asterisks indicate a statistically significant difference from the level of the aadA control strain using a two-tailed t-test. *: 0.001<P<0.05, **: P<0.001 (mean±s.d.; n=6). (b) Chronoamperometic measurements to estimate the sustained electron transfer from QA° to DMBQ in the presence of DCMU. The slope of current rise, which relates to the reduction rate of DMBQ, was estimated at 5 and 15 min after the addition of DCMU and normalized to the slope at 2.5 min before the DCMU addition (see Methods for details). Asterisks indicate a statistically significant difference from the level of the aadA control strain using a two-tailed t-test. *: 0.001<P<0.05, **: P<0.001. Error bars are s.d. of at least four independently performed experiments.

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