Fig 3. Modification of the conserved amino acid at position 238 of the D1 protein increased electron abstraction from QA in Syn but not in tobacco.
A. Quantification of cyt c (cc) photoreduction by thylakoids of WT-aadA tobacco, WT-Syn, Syn D1-K238E or tobacco D1-R238E. In the absence (green) or following the addition of the herbicide DCMU (red). DCMU enhanced electron transfer by Syn thylakoids, but completely blocked electron transfer in tobacco. Data was collected in three independent experiments. Bars represent standard error. B. Oxygen evolution rates monitored as a measure of the light-dependent electron transfer from the PSII oxygen evolving center of mutated Syn and tobacco (K238E Syn, R238E tobacco, respectively). The exogenous electron acceptors used were DCBQ in the absence of DCMU (blue bars) or cyt c in the presence of the herbicide DCMU (grey bars).