Figure 3

Analysis of the psaA strains. A. Schematic depiction of mutant strains after the first and second rounds of recombination following transformation with the psaA construct. The psaA construct is integrated in the Synechocystis psaA gene. In psaA ^prim the nptI-sacB cassette interrupts the At psaA gene. In psaA ^sec, loss of the cassette leads to the reconstitution of the entire At psaA under the control of the native cyanobacterial promoter. Positions of the primers used for genotyping (P2, P7-10) are indicated. B. In vivo absorption spectra of WT, psaA ^prim and psaA ^sec Synechocystis strains. The peaks at 438 and 681 nm correspond to the maxima of Chl a absorption, the peak at 628 nm corresponds to the absorption maximum of PC. The spectra were normalized to the absorbance at 730 nm. C. Complete segregation of the generated Synechocystis psaA strains, as demonstrated by PCR analysis. Primer positions are given in A. Expected sizes of the amplicons generated by the used primer pairs were: P7/P8, 2 kbps; P7/P2, 3 kbps; P9/P10, 2.3 kbps. Negative control (n.c.) was included. D. Drop test of WT, psaA ^prim and psaA ^sec Synechocystis strains on selective media and under different light conditions. Liquid cultures at OD₇₃₀ of 0.4 were washed with BG11 without glucose and spotted (15 μl each) on non-selective BG11 medium or on BG11 containing 100 μg/ml kanamycin or 5% sucrose. When tested for autotrophic growth, cells were grown in continuous light at 30 μmol photons m^-2 s^-1 on BG11 without glucose. When grown in Light Activated Heterotrophic Growth (LAHG) conditions, the cells were incubated in the dark on BG11 supplemented with 5 mM glucose, and exposed to light for 5 min every 24 hours.