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

Photosystem II (PSII) is the multi-subunit light-driven oxidoreductase that drives photosynthetic electron transport using electrons extracted from water. To investigate the initial steps of PSII assembly, we used strains of the cyanobacterium Synechocystis sp. PCC 6803 arrested at early stages of PSII biogenesis and expressing affinity-tagged PSII subunits to isolate PSII reaction center assembly (RCII) complexes and their precursor D1 and D2 modules (D1mod and D2mod). RCII preparations isolated using either a His-tagged D2 or a FLAG-tagged PsbI subunit contained the previously described RCIIa and RCII* complexes that differ with respect to the presence of the Ycf39 assembly factor and high light-inducible proteins (Hlips) and a larger complex consisting of RCIIa bound to monomeric PSI. All RCII complexes contained the PSII subunits D1, D2, PsbI, PsbE, and PsbF and the assembly factors rubredoxin A and Ycf48, but we also detected PsbN, Slr1470, and the Slr0575 proteins, which all have plant homologs. The RCII preparations also contained prohibitins/stomatins (Phbs) of unknown function and FtsH protease subunits. RCII complexes were active in light-induced primary charge separation and bound chlorophylls (Chls), pheophytins, beta-carotenes, and heme. The isolated D1mod consisted of D1/PsbI/Ycf48 with some Ycf39 and Phb3, while D2mod contained D2/cytochrome b559 with co-purifying PsbY, Phb1, Phb3, FtsH2/FtsH3, CyanoP, and Slr1470. As stably bound, Chl was detected in D1mod but not D2mod, formation of RCII appears to be important for stable binding of most of the Chls and both pheophytins. We suggest that Chl can be delivered to RCII from either monomeric Photosystem I or Ycf39/Hlips complexes.

• MeSH
• chlorofyl metabolismus   MeSH
• feofytiny metabolismus   MeSH
• fotosystém I (proteinový komplex) metabolismus   MeSH
• fotosystém II (proteinový komplex) * metabolismus   MeSH
• Synechocystis * metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• chlorofyl MeSH
• feofytiny MeSH
• fotosystém I (proteinový komplex) MeSH
• fotosystém II (proteinový komplex) * MeSH