Fig. 2

Genomic maps and transcript levels of Synechocystis sp. PCC 6803 strains. The four constructed strains are Synechocystis sp. PCC 6803 wild-type control (WTc), Synechocystis sp. PCC 6803 lacking adc1 gene (Δadc1c), Synechocystis sp. PCC 6803 overexpressing proC gene (OXP), and Δadc1 mutant overexpressing proC gene (OXP/Δadc1). PCR analysis employing two pairs of specific primers (Supplementary information Table S1) was used to confirm the accurate integration and placement of each gene fragment into the Synechocystis genome. (A) The double homologous recombination of both Cm^R gene occurred between the conserved sequences of psbA2 gene in WTc and Δadc1c, and a proC:Cm^R fragment occurred between the conserved sequences of psbA2 gene in OXP and OXP/Δadc1 strains when compared to WT. (B) For PCR products using UP_psbA2-F and Dw_psbA2-R primers, (B.1) For OXP strain, Lane M: GeneRuler DNA ladder, Lanes OX1, OX2, and OX3: three clones no. 1–3 containing a 3.2 kb fragment of Up_psbA2-proC-Cm^R-Dw_psbA2, Lanes WT and WTc: negative controls of a 2.4 kb fragment in WT and a 2.2 kb fragment in WTc, respectively. (B.2) For OXP/Δadc1 strain, Lane M: GeneRuler DNA ladder, Lanes OX1 and OX2: two clones no. 1 and 2 containing a 3.2 kb fragment of Up_psbA2-proC-Cm^R-Dw_psbA2, Lanes Δadc1 and Δadc1c: negative controls of a 2.4 kb fragment in Δadc1 and a 2.2 kb fragment in Δadc1c, respectively. (C) For PCR products using ProC-F and Cm^R-R primers, (C.1) For OXP strain, Lane M: GeneRuler DNA ladder, Lanes OX1, OX2, and OX3: three clones no. 1–3 containing a 1.9 kb fragment of proC-Cm^R, Lanes WT and WTc: negative controls (no band) using WT and WTc as template, respectively. (C.2) For OXP/Δadc1 strain, Lane M: GeneRuler DNA ladder, Lanes Δadc1 and Δadc1c: negative controls (no band) using Δadc1 and Δadc1c as template, respectively, Lanes OX1 and OX2: two clones no. 1 and 2 containing a 1.9 kb fragment of proC-Cm^R. (D) Transcript levels of proC gene determined by RT-PCR using RT-ProC-F and RT-ProC-R primers (Additional file 1: Table S1) in WT, WTc, Δadc1, Δadc1c, and two overexpressing strains, including OXP and OXP/Δadc1. The 0.8% agarose gel electrophoresis of PCR products was performed from cells grown for 6 days in normal BG₁₁ medium. The 16s rRNA was used as reference. The cropped gels (in D) were taken from the original images of RT-PCR products on agarose gels as shown in Supplementary information Figure S1