Article Figures & Data
Figures
- Figure 1.
Construction and characterization of the flv4-2/OE mutant. A, Schematic representation of the insertion of flv4-2 operon into the Synechocystis chromosome under the control of the psbA2 gene promoter. B and C, Western blots were performed with protein samples isolated from cultures grown at air-level CO2 (LC; B) and at 3% CO2 (HC; C). Twenty micrograms of total protein from the cell extracts were loaded into each lane (= 100%), if not otherwise indicated. WT, wild type. [See online article for color version of this figure.]
- Figure 2.
Growth phenotype of wild-type and mutant strains. A and B, Growth curves were obtained with cells cultivated at 500-HL (A) or at 1,500-HL (B). C, The difference in color of cells grown for 7 d at corresponding light intensities. WT, wild type.
- Figure 3.
Car/Chl a ratio measured from cultures cultivated at standard GL conditions (black bars) and at high light intensity of 500-HL (gray bars). The cultures were adjusted to an OD750 = 0.6 before the measurements. Values are means ± sd of three independent experiments. WT, wild type.
- Figure 4.
Production of singlet oxygen in wild-type, ΔpsbA2, flv4-2/OE, and Δflv4 strains in the presence of 5 mm His upon illumination of the cells at 2,300 μmol photon m−2 s−1. The cultures were adjusted to a chlorophyll concentration of 5 µg mL−1. To demonstrate that the O2 uptake signal indeed arises from 1O2, 10 mm sodium azide, which is specific quencher of 1O2, was also applied. Because sodium azide inhibits O2 evolution, its 1O2 quenching effect was tested in the presence of DCMU in which the artifact that would arise from the decreased of O2 evolution rate could be avoided. The results are a mean ± sd of three independent experiments. NaN3, sodium azide; WT, wild type.
- Figure 5.
PSII photoinhibition kinetics in wild-type, ΔpsbA2, and flv4-2/OE strains. The strains were illuminated with white light intensity of 500 µmol photons m−2 s-1in the presence of lincomycin (300 µg mL−1). Oxygen evolution rates were measured in the presence of 2 mm DMBQ as an artificial electron acceptor. The cultures were adjusted to a chlorophyll concentration of 5 µg mL−1. Values are means ± sd of three independent experiments. WT, wild type.
- Figure 6.
Fluorescence induction curves from wild-type, ΔpsbA2, flv4-2/OE, and Δflv4 strains. Cells were dark adapted and then exposed to red actinic light of 120 µmol photons m−2 s−1. The cultures were adjusted to a chlorophyll concentration of 10 µg mL−1. AL, actinic light; WT, wild type. [See online article for color version of this figure.]
- Figure 7.
Decrease of maximal fluorescence induced by OCP-mediated NPQ upon illumination of cells with strong blue light intensity (750 µmol photons m−2 s−1). The cultures were adjusted to a chlorophyll concentration of 10 µg mL−1. The values shown are the mean ± sd of three independent experiments. WT, wild type. [See online article for color version of this figure.]
- Figure 8.
A, Protein immunoblots showing the content of ApcD, PC, and OCP in wild-type, ΔpsbA2, flv4-2/OE, and Δflv4 strains. Ten micrograms of total protein from the cell extract were loaded in each lane. B, Protein immunoblots showing the content of Flv4, Sll0218, and Flv2 in wild-type, PAL, CK, ΔApcDF, and ΔOCP mutants. Twenty micrograms of total protein from the cell extract were loaded in each lane (= 100%), if not otherwise stated. This is a representative picture of three independent immunoblots. C, Transcript accumulation of flv4-2 operon in the wild-type, PAL, CK, ΔApcDF, and ΔOCP mutants analyzed by real-time quantitative RT-PCR. Transcript abundance is shown as relative units. The transcript level of the rnpB gene is used as a reference. The results are the mean from three independent experiments ± sd. ApcD allophycocyanin D; PC, phycocyanin; rel unit, relative unit; WT, wild type.
- Figure 9.
Flash-induced chlorophyll fluorescence relaxation curves in darkness from wild-type, ΔpsbA2, flv4-2/OE, and Δflv4 strains, grown in LC conditions. The curves were recorded in the absence (closed symbols) and in the presence of 20 µM DBMIB (open symbols). The cultures were adjusted to a chlorophyll concentration of 5 µg mL−1. To facilitate the comparison of the curves, F0 and FmD values were normalized to 0 and 1, respectively. The fluorescence traces are the mean of three independent experiments. rel unit, relative unit; WT, wild type. [See online article for color version of this figure.]
- Figure 10.
The 77K fluorescence emission spectra of wild-type, ΔpsbA2, flv4-2/OE, and Δflv4 strains excited at 580 nm. The spectra were averaged from three independent experiments. Each spectrum was normalized to PSI fluorescence peak at 723 nm (set as 1). The cultures were adjusted to a chlorophyll concentration of 5 µg mL−1. WT, wild type. [See online article for color version of this figure.]
Tables
- Table I. Oxygen evolution rates in wild-type, Δflv4, ΔpsbA2, and flv4-2/OE strains with different electron acceptors and inhibitors
Steady state oxygen evolution (in µmol O2 mg−1 chlorophyll h−1) was measured with an oxygen electrode under saturating light conditions. The cultures were adjusted to a chlorophyll concentration of 5 µg mL−1. Each value is an average of at least three independent experiments ± sd.
Strains DMBQ (2 mm) DCBQ (0.5 mm) DBMIB (2 µm) Wild type 600 ± 11 493 ± 18 124 ± 2 Δflv4 540 ± 9 565 ± 17 90 ± 4 ΔpsbA2 565 ± 21 513 ± 21 120 ± 3 flv4-2/OE 641 ± 8 421 ± 10 134 ± 3 - Table II. Occurrence of different photoprotection mechanism in the genomes of representative strains of cyanobacteria and photosynthetic eukaryotes
The D1:2 copy homology analysis was performed with BLASTP (http://blast.ncbi.nlm.nih.gov). Part of the data were imported from Zhang et al. (2012). LHCII/I, Light-harvesting complex II/I; Pcb, chlorophyll a/b binding light-harvesting protein; LL, low light ecotype; HL, high light ecotype.
Organism Type Ecological Niche Antenna System flv4-2 Operon D1:2 Copy (Q130E) Cyanobacteria Synechocystis sp. PCC 6803 β Freshwater PBs + − Microcystis aeruginosa NIES-843 β Marine PBs + − Microcystis aeruginosa sp. PCC 7806 β Freshwater PBs + − Cyanothece sp. PCC 8801 β Freshwater PBs + − Cyanothece sp. ATCC 51142 β Marine PBs + + Anabaena sp. PCC 7120 β Freshwater PBs + + Trychodesmium IMS 101 β Marine PBs − + Synechococcus sp. PCC 7002 β Marine PBs − + Synechococcus elongatus PCC 7942 β Freshwater PBs − + Thermosynechococcus elongatus BP-1 β Freshwater-thermophile PBs − + Synechococcus sp. WH7803 α Marine PBs − + Synechococcus sp. WH8102 α Marine PBs − + Prochlorococcus marinus str. MIT9211 α Marine (LL) Pcb − − Prochlorococcus marinus MED4 α Marine (HL) Pcb − − Photosynthetic eukaryote Chlamydomonas reinhardtii Freshwater LHCII/I − + Arabidopsis Land LHCII/I − +
Supplemental Data
Supplemental Figures and Table
Files in this Data Supplement:
- Supplemental Data - Supplemental Figures 1-7 and Supplemental Table
