Light quality significantly influences plant metabolism, growth and development. Recently, we have demonstrated that leaves of barley and other plant species grown under monochromatic green light (500-590 nm) accumulated a large pool of chlorophyll a (Chl a) intermediates with incomplete hydrogenation of their phytyl chains. In this work, we studied accumulation of these geranylgeranylated Chls a and b in pigment-protein complexes (PPCs) of Arabidopsis plants acclimated to green light and their structural-functional consequences on the photosynthetic apparatus. We found that geranylgeranylated Chls are present in all major PPCs, although their presence was more pronounced in light-harvesting complex II (LHCII) and less prominent in supercomplexes of photosystem II (PSII). Accumulation of geranylgeranylated Chls hampered the formation of PSII and PSI super- and megacomplexes in the thylakoid membranes as well as their assembly into chiral macrodomains; it also lowered the temperature stability of the PPCs, especially that of LHCII trimers, which led to their monomerization and an anomaly in the photoprotective mechanism of non-photochemical quenching. Role of geranylgeranylated Chls in adverse effects on photosynthetic apparatus of plants acclimated to green light is discussed.

• MeSH
• adaptace oční fyziologie   MeSH
• Arabidopsis metabolismus   MeSH
• chlorofyl metabolismus   MeSH
• fotosystém II (proteinový komplex) metabolismus   MeSH
• prenylace MeSH
• světlosběrné proteinové komplexy metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH

Low oxygen conditions occur in grass sites due to high and frequent precipitation, poor soil quality, and over-irrigation followed by slow drainage. Three warm-season and one cool-season grass were analyzed at metabolic level during a time-course experiment performed in a controlled anoxic environment. Prolonged oxygen depletion proved detrimental by leading to premature death to all the species, with the exception of seashore paspalum. Moreover, the anoxia tolerance observed in these grasses has been associated with slow use of carbohydrates, rather than with their relative abundance, which was more important than their antioxidant capacity. Further physiological characterization of eight seashore paspalum genotypes to anoxia was also performed, by examining the variation in photosystem II (PSII) efficiency and gas exchange during post-anoxia recovery. Multivariate analysis highlighted the presence of three main clusters of seashore paspalum genotypes, characterized by different ability to restore the PSII photochemistry during recovery after one day of anoxia. Taken together, our data demonstrate that the analysis of post-anoxia recovery of fluorescence and gas exchange parameters can represent a fast and reliable indicator for selecting species and cultivars more able to acclimate their photosynthetic apparatus.

• MeSH
• alkoholdehydrogenasa metabolismus   MeSH
• anaerobióza účinky záření   MeSH
• cukry metabolismus   MeSH
• druhová specificita MeSH
• faktorová analýza statistická MeSH
• fotosyntéza * účinky záření   MeSH
• fotosystém II (proteinový komplex) metabolismus   MeSH
• fyziologická adaptace účinky záření   MeSH
• genotyp MeSH
• kvantitativní znak dědičný * MeSH
• kyslík metabolismus   MeSH
• lipnicovité enzymologie   genetika   fyziologie   účinky záření   MeSH
• roční období MeSH
• rozpustnost MeSH
• světlo MeSH
• Publikační typ
• časopisecké články MeSH

The cyanobacterium Synechocystis sp. PCC 6803 contains four members of the FtsH protease family. One of these, FtsH (slr0228), has been implicated recently in the repair of photodamaged photosystem II (PSII) complexes. We have demonstrated here, using a combination of blue native PAGE, radiolabeling, and immunoblotting, that FtsH (slr0228) is required for selective replacement of the D1 reaction center subunit in both wild type PSII complexes and in PSII subcomplexes lacking the PSII chlorophyll a-binding subunit CP43. To test whether FtsH (slr0228) has a more general role in protein quality control in vivo, we have studied the synthesis and degradation of PSII subunits in wild type and in defined insertion and missense mutants incapable of proper assembly of the PSII holoenzyme. We discovered that, when the gene encoding FtsH (slr0228) was disrupted in these strains, the overall level of assembly intermediates and unassembled PSII proteins markedly increased. Pulse-chase experiments showed that this was due to reduced rates of degradation in vivo. Importantly, analysis of epitope-tagged and green fluorescent protein-tagged strains revealed that slr0228 was present in the thylakoid and not the cytoplasmic membrane. Overall, our results show that FtsH (slr0228) plays an important role in controlling the removal of PSII subunits from the thylakoid membrane and is not restricted to selective D1 turnover.

• MeSH
• 2D gelová elektroforéza MeSH
• biochemické jevy MeSH
• biochemie MeSH
• buněčná membrána metabolismus   MeSH
• časové faktory MeSH
• chloroplasty metabolismus   MeSH
• elektroforéza v polyakrylamidovém gelu MeSH
• epitopy chemie   MeSH
• financování organizované MeSH
• fotosystém II (proteinový komplex) metabolismus   MeSH
• genotyp MeSH
• imunoblotting MeSH
• konfokální mikroskopie MeSH
• metaloendopeptidasy fyziologie   chemie   MeSH
• missense mutace MeSH
• mutace MeSH
• plazmidy metabolismus   MeSH
• proteasy chemie   MeSH
• světlo MeSH
• Synechocystis metabolismus   MeSH
• tylakoidy metabolismus   MeSH
• vazba proteinů MeSH
• zelené fluorescenční proteiny chemie   metabolismus   MeSH

The membrane-embedded FtsH proteases found in bacteria, chloroplasts, and mitochondria are involved in diverse cellular processes including protein quality control and regulation. The genome of the model cyanobacterium Synechocystis sp PCC 6803 encodes four FtsH homologs designated FtsH1 to FtsH4. The FtsH3 homolog is present in two hetero-oligomeric complexes: FtsH2/3, which is responsible for photosystem II quality control, and the essential FtsH1/3 complex, which helps maintain Fe homeostasis by regulating the level of the transcription factor Fur. To gain a more comprehensive insight into the physiological roles of FtsH hetero-complexes, we performed genome-wide expression profiling and global proteomic analyses of Synechocystis mutants conditionally depleted of FtsH3 or FtsH1 grown under various nutrient conditions. We show that the lack of FtsH1/3 leads to a drastic reduction in the transcriptional response to nutrient stress of not only Fur but also the Pho, NdhR, and NtcA regulons. In addition, this effect is accompanied by the accumulation of the respective transcription factors. Thus, the FtsH1/3 complex is of critical importance for acclimation to iron, phosphate, carbon, and nitrogen starvation in Synechocystis.plantcell;31/12/2912/FX1F1fx1.

• MeSH
• aklimatizace genetika   MeSH
• bakteriální proteiny genetika   metabolismus   MeSH
• dusík nedostatek   metabolismus   MeSH
• exprese genu MeSH
• fosfáty nedostatek   metabolismus   MeSH
• fosforylace MeSH
• fotosystém II (proteinový komplex) chemie   genetika   metabolismus   MeSH
• metaloproteasy genetika   metabolismus   MeSH
• mutace MeSH
• proteiny vázající fosfáty genetika   metabolismus   MeSH
• proteolýza MeSH
• proteom genetika   metabolismus   MeSH
• proteomika MeSH
• regulace genové exprese u bakterií genetika   MeSH
• regulon genetika   MeSH
• represorové proteiny genetika   metabolismus   MeSH
• ribozomální proteiny genetika   metabolismus   MeSH
• Synechocystis enzymologie   metabolismus   MeSH
• transkripční faktory genetika   metabolismus   MeSH
• uhlík nedostatek   metabolismus   MeSH
• živiny nedostatek   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH