Nejvíce citovaný článek - PubMed ID 24838684
One potential approach to improve the productivity of cyanobacteria and microalgae is to enhance photosynthetic efficiency by introducing far-red absorbing pigment molecules (such as chlorophylls f and d) into the photosynthetic apparatus to expand the range of photosynthetically active radiation. We have shown previously that expressing the ChlF subunit of Chroococcidiopsis thermalis PCC 7203 in the model cyanobacterium Synechocystis sp. PCC 6803 (Syn6803) is sufficient to drive the production of chlorophyll f (Chl f), but only to low levels (0.24% Chl f/Chl a). By using the strong Pcpc560 promoter and an N-terminal truncated derivative of ChlF, we have been able to increase the yield of Chl f in white light by over 30-fold to about 8.2% Chl f/Chl a, close to the level displayed by far-red photoacclimated C. thermalis 7203. Additionally, we demonstrate that ChlF from Fisherella thermalis PCC 7521, like ChlF from C. thermalis 7203, assembles into a variant of the monomeric photosystem II (PSII) core complex termed the super-rogue PSII complex when expressed in Syn6803. This contrasts with the originally reported formation of a ChlF homodimeric complex in Synechococcus sp. PCC 7002. Overall, our work is an important starting point for mechanistic and structural studies of super-rogue PSII and for incorporating Chl f into the photosynthetic apparatus of Syn6803.
- MeSH
- bakteriální proteiny metabolismus genetika MeSH
- chlorofyl * analogy a deriváty metabolismus biosyntéza MeSH
- fotosyntéza MeSH
- fotosystém II (proteinový komplex) metabolismus MeSH
- světlo MeSH
- Synechocystis * metabolismus genetika MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- bakteriální proteiny MeSH
- chlorofyl * MeSH
- chlorophyll f MeSH Prohlížeč
- fotosystém II (proteinový komplex) MeSH
The growth of plants, algae, and cyanobacteria relies on the catalytic activity of the oxygen-evolving PSII complex, which uses solar energy to extract electrons from water to feed into the photosynthetic electron transport chain. PSII is proving to be an excellent system to study how large multi-subunit membrane-protein complexes are assembled in the thylakoid membrane and subsequently repaired in response to photooxidative damage. Here we summarize recent developments in understanding the biogenesis of PSII, with an emphasis on recent insights obtained from biochemical and structural analysis of cyanobacterial PSII assembly/repair intermediates. We also discuss how chlorophyll synthesis is synchronized with protein synthesis and suggest a possible role for PSI in PSII assembly. Special attention is paid to unresolved and controversial issues that could be addressed in future research.
The extrinsic PsbU and PsbV proteins are known to play a critical role in stabilizing the Mn4CaO5 cluster of the PSII oxygen-evolving complex (OEC). However, most isolates of the marine cyanobacterium Prochlorococcus naturally miss these proteins, even though they have kept the main OEC protein, PsbO. A structural homology model of the PSII of such a natural deletion mutant strain (P. marinus MED4) did not reveal any obvious compensation mechanism for this lack. To assess the physiological consequences of this unusual OEC, we compared oxygen evolution between Prochlorococcus strains missing psbU and psbV (PCC 9511 and SS120) and two marine strains possessing these genes (Prochlorococcus sp. MIT9313 and Synechococcus sp. WH7803). While the low light-adapted strain SS120 exhibited the lowest maximal O2 evolution rates (Pmax per divinyl-chlorophyll a, per cell or per photosystem II) of all four strains, the high light-adapted strain PCC 9511 displayed even higher PChlmax and PPSIImax at high irradiance than Synechococcus sp. WH7803. Furthermore, thermoluminescence glow curves did not show any alteration in the B-band shape or peak position that could be related to the lack of these extrinsic proteins. This suggests an efficient functional adaptation of the OEC in these natural deletion mutants, in which PsbO alone is seemingly sufficient to ensure proper oxygen evolution. Our study also showed that Prochlorococcus strains exhibit negative net O2 evolution rates at the low irradiances encountered in minimum oxygen zones, possibly explaining the very low O2 concentrations measured in these environments, where Prochlorococcus is the dominant oxyphototroph.
- Klíčová slova
- Marine cyanobacteria, Oxygen minimum zones, Oxygen-evolving complex, Photoacclimation, Photosystem II, Prochlorococcus, Synechococcus,
- MeSH
- bakteriální proteiny chemie genetika fyziologie MeSH
- chlorofyl metabolismus MeSH
- fotosyntéza fyziologie MeSH
- fotosystém II (proteinový komplex) chemie genetika fyziologie MeSH
- genom bakteriální MeSH
- kyslík metabolismus MeSH
- molekulární modely MeSH
- průtoková cytometrie MeSH
- sinice genetika metabolismus MeSH
- světlo MeSH
- Publikační typ
- časopisecké články MeSH
- srovnávací studie MeSH
- Názvy látek
- bakteriální proteiny MeSH
- chlorofyl MeSH
- fotosystém II (proteinový komplex) MeSH
- kyslík MeSH
Robust photosynthesis in chloroplasts and cyanobacteria requires the participation of accessory proteins to facilitate the assembly and maintenance of the photosynthetic apparatus located within the thylakoid membranes. The highly conserved Ycf48 protein acts early in the biogenesis of the oxygen-evolving photosystem II (PSII) complex by binding to newly synthesized precursor D1 subunit and by promoting efficient association with the D2 protein to form a PSII reaction center (PSII RC) assembly intermediate. Ycf48 is also required for efficient replacement of damaged D1 during the repair of PSII. However, the structural features underpinning Ycf48 function remain unclear. Here we show that Ycf48 proteins encoded by the thermophilic cyanobacterium Thermosynechococcus elongatus and the red alga Cyanidioschyzon merolae form seven-bladed beta-propellers with the 19-aa insertion characteristic of eukaryotic Ycf48 located at the junction of blades 3 and 4. Knowledge of these structures has allowed us to identify a conserved "Arg patch" on the surface of Ycf48 that is important for binding of Ycf48 to PSII RCs but also to larger complexes, including trimeric photosystem I (PSI). Reduced accumulation of chlorophyll in the absence of Ycf48 and the association of Ycf48 with PSI provide evidence of a more wide-ranging role for Ycf48 in the biogenesis of the photosynthetic apparatus than previously thought. Copurification of Ycf48 with the cyanobacterial YidC protein insertase supports the involvement of Ycf48 during the cotranslational insertion of chlorophyll-binding apopolypeptides into the membrane.
- Klíčová slova
- chlorophyll-binding proteins, photosynthesis, photosystem II,
- MeSH
- bakteriální proteiny genetika metabolismus MeSH
- fotosystém I (proteinový komplex) biosyntéza genetika MeSH
- fotosystém II (proteinový komplex) biosyntéza genetika MeSH
- sinice genetika metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- bakteriální proteiny MeSH
- fotosystém I (proteinový komplex) MeSH
- fotosystém II (proteinový komplex) MeSH
The extrinsic proteins of photosystem II of higher plants and green algae PsbO, PsbP, PsbQ, and PsbR are essential for stable oxygen production in the oxygen evolving center. In the available X-ray crystallographic structure of higher plant PsbQ residues S14-Y33 are missing. Building on the backbone NMR assignment of PsbQ, which includes this "missing link", we report the extended resonance assignment including side chain atoms. Based on nuclear Overhauser effect spectra a high resolution solution structure of PsbQ with a backbone RMSD of 0.81 Å was obtained from torsion angle dynamics. Within the N-terminal residues 1-45 the solution structure deviates significantly from the X-ray crystallographic one, while the four-helix bundle core found previously is confirmed. A short α-helix is observed in the solution structure at the location where a β-strand had been proposed in the earlier crystallographic study. NMR relaxation data and unrestrained molecular dynamics simulations corroborate that the N-terminal region behaves as a flexible tail with a persistent short local helical secondary structure, while no indications of forming a β-strand are found.
- Klíčová slova
- Spinacia oleracea, dynamic N-terminus, extrinsic photosynthetic protein, hydrogen bond dynamics, intrinsic disorder, solution structure,
- MeSH
- fotosystém II (proteinový komplex) chemie genetika metabolismus MeSH
- krystalografie rentgenová MeSH
- magnetická rezonanční spektroskopie metody MeSH
- rekombinantní proteiny chemie metabolismus MeSH
- rostlinné proteiny chemie genetika metabolismus MeSH
- roztoky MeSH
- sekundární struktura proteinů * MeSH
- sekvence aminokyselin MeSH
- simulace molekulární dynamiky * MeSH
- Spinacia oleracea genetika metabolismus MeSH
- terciární struktura proteinů MeSH
- termodynamika MeSH
- vazba proteinů MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- fotosystém II (proteinový komplex) MeSH
- rekombinantní proteiny MeSH
- rostlinné proteiny MeSH
- roztoky MeSH
