Reciprocal Expression of Two Candidate Di-Iron Enzymes Affecting Photosystem I and Light-Harvesting Complex Accumulation

Moseley, Jeffrey L.; Page, M. Dudley; Alder, Nancy P.; Eriksson, Mats; Quinn, Jeanette M.; Soto, Feiris; Theg, Steven M.; Hippler, Michael; Merchant, Sabeeha

doi:10.1105/tpc.010420

Cited by 131 publications

(117 citation statements)

References 56 publications

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“…We used bacteriophage EMBL3 with a 13-kb insert (9) isolated from an infected culture of Escherichia coli NM539 (10). The bacteria were grown in LB medium supplemented with 10 mM MgSO 4 and 0.5% maltose.…”

Section: Methodsmentioning

confidence: 99%

Osmotic pressure inhibition of DNA ejection from phage

Evilevitch

Lavelle

Knobler

et al. 2003

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

304

381

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Bacterial viral capsids in aqueous solution can be opened in vitro by addition of their specific receptor proteins, with consequent full ejection of their genomes. We demonstrate that it is possible to control the extent of this ejection by varying the external osmotic pressure. In the particular case of bacteriophage , the ejection is 50% inhibited by osmotic pressures (of polyethylene glycol) comparable to those operative in the cytoplasm of host bacteria; it is completely suppressed by a pressure of 20 atmospheres. Furthermore, our experiments monitor directly a dramatic decrease of the stress inside the unopened phage capsid upon addition of polyvalent cations to the host solution, in agreement with many recent theories of DNA interactions.V iral capsids are often highly pressurized. In the case of double-stranded DNA bacteriophages, for example, there are large forces acting to push the genome out through the tail of the viral particle. Recent experiments (1) and theory (2, 3) have established that the forces inside these capsids reach very high values (of order 50 pN) when the genomes are fully packaged. These forces are estimated to correspond to pressures of the order of 50 atm (1 atm ϭ 101.3 kPa; refs. 1-4). Such high values of stress result from the DNA being strongly bent and confined. Specifically, the inner diameter of the capsid is comparable to the DNA persistence length (50 nm), and the typical interaxial spacings are small enough (2.5 nm; ref. 5) that neighboring chains experience strong repulsions. It is precisely these forces that drive the ejection of the genome into the host cell after the tail of the capsid has been bound to its receptor protein in the outer cell membrane; equivalently, it is these forces that must be exerted by the motor protein responsible for packaging of the viral genome (1).Previous in vitro experiments have demonstrated that DNA ejection is fast (occurring on a time scale of seconds) and complete when phage capsids are opened by their receptors in aqueous solution (6). The capsids are permeable to water and salt ions, so there is no difference in hydrostatic pressure between the inside and outside of the capsid, and osmotic equilibrium is also maintained (7). The pressure difference between the capsid and the solution is therefore associated only with the confinement of the DNA. When the capsid is opened, ejection proceeds until this pressure difference falls to zero. Clearly, at this point the force driving the ejection has also dropped to zero. For the in vivo situation, however, ejection does not occur into a simple salt solution. The DNA is ejected into a highly concentrated colloidal suspension, the cell cytoplasm, which is characterized by high concentrations of proteins and other macromolecular structures. In general, then, one expects this colloidal solution to give rise to a force that resists the entry of DNA (8). More explicitly, because the ejection force associated with stress inside the capsid drops monotonically as the ejection proceeds, there will be a...

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Section: Methodsmentioning

confidence: 99%

Osmotic pressure inhibition of DNA ejection from phage

Evilevitch

Lavelle

Knobler

et al. 2003

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

304

381

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“…Two isoforms of AcsF in the unicellular alga Chlamydomonas reinhardtii, CRD1 and CTH1, catalyze E ring formation under copper-deficient and -replete conditions, respectively (12,16). These proteins are localized to both the thylakoid membrane and chloroplast envelope (17), a pattern shared with the single AcsF in Arabidopsis thaliana, CHL27 (10,18).…”

mentioning

confidence: 97%

“…gelatinosus contains both BchE and AcsF cyclases, conferring the ability to synthesize BChl under varying O 2 regimes (9). Orthologs of acsF are widely distributed in phototrophs and have been studied in higher plants (10,11), algae (12) and cyanobacteria (13), the green nonsulfur bacterium Chloroflexus aurantiacus (14), and the purple alphaproteobacterium Rhodobacter (Rba.) sphaeroides (15) (Fig.…”

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confidence: 99%

Three classes of oxygen-dependent cyclase involved in chlorophyll and bacteriochlorophyll biosynthesis

Chen

Canniffe

Hunter

2017

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

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The biosynthesis of (bacterio)chlorophyll pigments is among the most productive biological pathways on Earth. Photosynthesis relies on these modified tetrapyrroles for the capture of solar radiation and its conversion to chemical energy. (Bacterio)chlorophylls have an isocyclic fifth ring, the formation of which has remained enigmatic for more than 60 y. This reaction is catalyzed by two unrelated cyclase enzymes using different chemistries. The majority of anoxygenic phototrophic bacteria use BchE, an O 2 -sensitive [4Fe-4S] cluster protein, whereas plants, cyanobacteria, and some phototrophic bacteria possess an O 2 -dependent enzyme, the major catalytic component of which is a diiron protein, AcsF. Plant and cyanobacterial mutants in ycf54 display impaired function of the O 2 -dependent enzyme, accumulating the reaction substrate. Swapping cyclases between cyanobacteria and purple phototrophic bacteria reveals three classes of the O 2 -dependent enzyme. AcsF from the purple betaproteobacterium Rubrivivax (Rvi.) gelatinosus rescues the loss not only of its cyanobacterial ortholog, cycI, in Synechocystis sp. PCC 6803, but also of ycf54; conversely, coexpression of cyanobacterial cycI and ycf54 is required to complement the loss of acsF in Rvi. gelatinosus. These results indicate that Ycf54 is a cyclase subunit in oxygenic phototrophs, and that different classes of the enzyme exist based on their requirement for an additional subunit. AcsF is the cyclase in Rvi. gelatinosus, whereas alphaproteobacterial cyclases require a newly discovered protein that we term BciE, encoded by a gene conserved in these organisms. These data delineate three classes of O 2 -dependent cyclase in chlorophototrophic organisms from higher plants to bacteria, and their evolution is discussed herein.

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“…Thus, R. gelatinosus possesses two unrelated MgPME cyclases, one oxygen-dependent and one oxygen-independent (16,17). AcsF homologs have since been identified in many photosynthetic eukaryotes including C. reinhardtii (18), Arabidopsis thaliana (19), and barley (15). Two acsF-like genes, sll1214 and sll1874, have been identified in Synechocystis PCC 6803 (hereafter Synechocystis) (20); Sll1214 is essential for growth under aerobic conditions (20) and, to a certain extent, micro-oxic conditions (21), whereas Sll1874 was found to be essential for growth in micro-oxic conditions (20,21).…”

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confidence: 99%