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Nomura, C. T.Persson, S.Shen, G.Inoue-Sakamoto, K.Bryant, D. A.
Characterization of two cytochrome oxidase operons in the marine cyanobacterium Synechococcus sp. PCC 7002: inactivation of ctaDI affects the PS I:PS II ratio.
Photosynth Res. 2006 Feb;87(2):215-28. Epub 2006 Jan 21. PMID:16437183 | Abstract | MeSH | Related Articles | Sections | Gene Index |
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Cyanobacteria have versatile electron transfer pathways and many of the proteins involved are functional in both respiratory and photosynthetic electron transport. Examples of such proteins include the cytochrome b (6) f complex, NADH dehydrogenase and cytochrome oxidase complexes. In this study we have cloned and sequenced two gene clusters from the marine cyanobacterium Synechococcus sp. PCC 7002 that potentially encode heme-copper cytochrome oxidases. The ctaCIDIEI and ctaCIIDIIEII gene clusters are most similar to two related gene clusters found in the freshwater cyanobacterial strain Synechocystis sp. PCC 6803. Unlike Synechocystis sp. PCC 6803, Synechococcus sp. PCC 7002 does not have a cydAB-like gene cluster which encodes a quinol oxidase. The ctaCIDIEI and ctaCIIDIIEII gene clusters were transcribed polycistronically, although the levels of transcripts for the ctaCIIDIIEII gene cluster were lower than those of the ctaCIDIEI gene cluster. The ctaDI and ctaDII coding sequences were interrupted by interposon mutagenesis and full segregants were isolated and characterized for both single and double mutants. Growth rates, chlorophyll and carotenoid contents, oxygen consumption and oxygen evolution were examined in the wild type and mutant strains. Differences between the wild type and mutant strains observed in 77 K fluorescence spectra and in pulse-amplified modulated (PAM) fluorescence studies suggest that the cyanobacterial oxidases play a role in photoinhibition and high light tolerance in Synechococcus sp. PCC 7002.
MeSH terms
1. Amino Acid Sequence
2. Carotenoids/metabolism
3. Chlorophyll/metabolism
4. Cloning, Molecular
5. Electron Transport Complex IV/*genetics
6. Gene Deletion
7. Gene Expression Regulation, Bacterial
8. Kinetics
9. Molecular Sequence Data
10. Multigene Family
11. Operon/*genetics
12. Oxidation-Reduction
13. Oxygen/metabolism
14. Oxygen Consumption
15. Photosystem I Protein Complex/chemistry/genetics/*metabolism
16. Photosystem II Protein Complex/chemistry/genetics/*metabolism
17. Spectrometry, Fluorescence
18. Synechococcus/*enzymology/*genetics
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Nomura, C. T.Sakamoto, T.Bryant, D. A.
Roles for heme-copper oxidases in extreme high-light and oxidative stress response in the cyanobacterium Synechococcus sp. PCC 7002.
Arch Microbiol. 2006 Jun;185(6):471-9. Epub 2006 Apr 27. PMID:16775753 | Abstract | MeSH | Related Articles | Sections | Gene Index |
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The ctaCIDIEI and ctaCIIDIIEII gene clusters that encode heme-copper cytochrome oxidases have been characterized in the marine cyanobacterium Synechococcus sp. PCC 7002 and the inactivation of ctaDI was shown to affect high-light adaptation. In this study, Synechococcus sp. PCC 7002 wild-type, ctaDI, ctaDII, and ctaDI-ctaDII double mutants were grown under extreme high-light and oxidative stress to further assess the roles of cytochrome oxidases in cyanobacteria. Cells of the ctaDI mutant strain barely grew under extreme high-light illumination of 4.5 mE m(-2) s(-1), suggesting that CtaDI is required for high-light acclimation in Synechococcus sp. PCC 7002. The ctaDI-ctaDII double mutant cells unexpectedly tolerated extreme high-light intensity, indicating that the disruption of ctaDII gene suppresses the high-light sensitivity phenotype of the ctaDI single mutant. The ctaDII mutant cells also exhibited higher tolerance to the oxidative stress compound, methyl viologen, in the growth media. The ctaDII mutant and the ctaDI-ctaDII double mutant cells had approximately twofold higher levels of superoxide dismutase (SOD) activity, indicating that the disruption of ctaDII gene increased the capacity to decompose active oxygen species. These results suggest that the CtaII cytochrome oxidase may be involved with the oxidative stress response, including the control of SOD expression.
MeSH terms
1. Bacterial Proteins
2. Catalase/metabolism
3. Chlorophyll/metabolism
4. Cyanobacteria/drug effects/growth & development/*metabolism
5. Heme/metabolism
6. Hydrogen Peroxide/metabolism
7. *Light
8. Microbial Viability/drug effects/radiation effects
9. Oxidation-Reduction
10. Oxidative Stress
11. Oxidoreductases/metabolism/*physiology
12. Oxygen/metabolism
13. Paraquat/pharmacology
14. Peroxidases/metabolism
15. Photosynthesis/radiation effects
16. Superoxide Dismutase/metabolism

0.287460359 [0.132863971, 0.168002363, 0.260851789, 0.265599949, 0.285180104]

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