Phycobilisome core mutants of Synechocystis PCC 6803

Ajlani, Ghada; Vernotte, C.; DiMagno, Lisa; Haselkorn, Robert

doi:10.1016/0005-2728(95)00086-x

Cited by 83 publications

(94 citation statements)

References 23 publications

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“…and G.A., unpublished work), and AB (⌬apcAB) producing PC only and assembling uncoupled rods (20) (Fig. 1A).…”

Section: Fnr Undergoes Proteolysis In Rodless Pbs Mutantsmentioning

confidence: 85%

“…FNR S accumulation, in the WT during heterotrophic growth, and the impairment of heterotrophic growth in MI6, suggest that the attachment to PBS is a hindrance for the FNR activity required under these conditions (NADPH consumption). It is possible that in mutants such as CK, AB, and PAL, containing a higher photosystem II/photosystem I ratio caused by PBS deficiencies (20,21), FNR S accumulation (visible in Fig. 1CЈ) is caused by an excess of NADPH.…”

Section: Discussionmentioning

confidence: 99%

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A second isoform of the ferredoxin:NADP oxidoreductase generated by an in-frame initiation of translation

Thomas

Ughy

Lagoutte

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

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100

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Ferredoxin:NADP oxidoreductases (FNRs) constitute a family of flavoenzymes that catalyze the exchange of reducing equivalents between one-electron carriers and the two-electron-carrying NADP(H). The main role of FNRs in cyanobacteria and leaf plastids is to provide the NADPH for photoautotrophic metabolism. In root plastids, a distinct FNR isoform is found that has been postulated to function in the opposite direction, providing electrons for nitrogen assimilation at the expense of NADPH generated by heterotrophic metabolism. A multiple gene family encodes FNR isoenzymes in plants, whereas there is only one FNR gene (petH) in cyanobacteria. Nevertheless, we detected two FNR isoforms in the cyanobacterium Synechocystis sp. strain PCC6803. One of them (FNR S Ϸ34 kDa) is similar in size to the plastid FNR and specifically accumulates under heterotrophic conditions, whereas the other one (FNRL Ϸ46 kDa) contains an extra N-terminal domain that allows its association with the phycobilisome. Site-directed mutants allowed us to conclude that the smaller isoform, FNR S, is produced from an internal ribosome entry site within the petH ORF. Thus we have uncovered a mechanism by which two isoforms are produced from a single gene, which is, to our knowledge, novel in photosynthetic bacteria. Our results strongly suggest that FNRL is an NADP ؉ reductase, whereas FNRS is an NADPH oxidase.

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“…and G.A., unpublished work), and AB (⌬apcAB) producing PC only and assembling uncoupled rods (20) (Fig. 1A).…”

Section: Fnr Undergoes Proteolysis In Rodless Pbs Mutantsmentioning

confidence: 85%

Section: Discussionmentioning

confidence: 99%

A second isoform of the ferredoxin:NADP oxidoreductase generated by an in-frame initiation of translation

Thomas

Ughy

Lagoutte

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

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100

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“…The protocol used derives from that described by Ajlani et al (1995). After reaching optical density at 800 nm = 1, cyanobacteria cells were harvested through centrifugation at 54,00g, 23°C, for 6 min.…”

Section: Isolation Of Pbsmentioning

confidence: 99%

“…Each Rep domain interacts with an APC trimer situated in different cylinders, which stabilizes the core of PB (Zhao et al, 1992;Shen et al, 1993;Ajlani et al, 1995;Ajlani and Vernotte, 1998). The ApcE protein also determines the number of APC cylinders that form the PB core (Capuano et al, 1991(Capuano et al, , 1993.…”

mentioning

confidence: 99%

Specificity of the Cyanobacterial Orange Carotenoid Protein: Influences of Orange Carotenoid Protein and Phycobilisome Structures

et al. 2013

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Cyanobacteria have developed a photoprotective mechanism that decreases the energy arriving at the reaction centers by increasing thermal energy dissipation at the level of the phycobilisome (PB), the extramembranous light-harvesting antenna. This mechanism is triggered by the photoactive Orange Carotenoid Protein (OCP), which acts both as the photosensor and the energy quencher. The OCP binds the core of the PB. The structure of this core differs in diverse cyanobacterial strains. Here, using two isolated OCPs and four classes of PBs, we demonstrated that differences exist between OCPs related to PB binding, photoactivity, and carotenoid binding. Synechocystis PCC 6803 (hereafter Synechocystis) OCP, but not Arthrospira platensis PCC 7345 (hereafter Arthrospira) OCP, can attach echinenone in addition to hydroxyechinenone. Arthrospira OCP binds more strongly than Synechocystis OCP to all types of PBs. Synechocystis OCP can strongly bind only its own PB in 0.8 M potassium phosphate. However, if the Synechocystis OCP binds to the PB at very high phosphate concentrations (approximately 1.4 M), it is able to quench the fluorescence of any type of PB, even those isolated from strains that lack the OCP-mediated photoprotective mechanism. Thus, the determining step for the induction of photoprotection is the binding of the OCP to PBs. Our results also indicated that the structure of PBs, at least in vitro, significantly influences OCP binding and the stabilization of OCP-PB complexes. Finally, the fact that the OCP induced large fluorescence quenching even in the two-cylinder core of Synechococcus elongatus PBs strongly suggested that OCP binds to one of the basal allophycocyanin cylinders.

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“…Phycobilisomes were prepared from Synechocystis sp. strain PCC6803 as described by Ajlani et al (1995) and Glazer (1988). Absorption spectra were recorded on a Varian Cary-5E double-beam spectrophotometer, with a data interval of 0?5 nm.…”

mentioning

confidence: 99%

Phycobilisome rod mutants in Synechocystis sp. strain PCC6803

Ughy

Ajlani

2004

Microbiology

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The phycobilisome is a large pigment-protein assembly that harvests light energy for photosynthesis. This supramolecular complex is composed of two main structures: a core substructure and peripheral rods. Linker polypeptides assemble phycobiliproteins within these structures and optimize light absorption and energy transfer. Mutations have been constructed in three rod-linker-coding genes located in the cpc operon of Synechocystis sp. strain PCC6803. The cpcC1 gene encoding the 33 kDa linker is found to be epistatic to cpcC2 encoding the 30 kDa linker, indicating a specific role for each of these two linkers in rod growth. This corroborates studies on the sequential degradation of phycobilisomes upon nitrogen starvation. Three allelic mutants affecting cpcC2 revealed a polar effect of commonly used cassettes (aphI, aadA) on the operon steady-state transcripts and an effect of rod linker availability on the amount of phycocyanin incorporated in the phycobilisome. This led to the proposal that regulation of rod length could occur through processing of transcripts upstream of the cpcC2 gene.

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Phycobilisome core mutants of Synechocystis PCC 6803

Cited by 83 publications

References 23 publications

A second isoform of the ferredoxin:NADP oxidoreductase generated by an in-frame initiation of translation

A second isoform of the ferredoxin:NADP oxidoreductase generated by an in-frame initiation of translation

Specificity of the Cyanobacterial Orange Carotenoid Protein: Influences of Orange Carotenoid Protein and Phycobilisome Structures

Phycobilisome rod mutants in Synechocystis sp. strain PCC6803

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