The negatively charged lipid phosphatidylglycerol (PG) constitutes up to 10% of total lipids in photosynthetic membranes, and its deprivation in cyanobacteria is accompanied by chlorophyll (Chl) depletion. Indeed, radioactive labeling of the PG-depleted ΔpgsA mutant of Synechocystis sp. strain PCC 6803, which is not able to synthesize PG, proved the inhibition of Chl biosynthesis caused by restriction on the formation of 5-aminolevulinic acid and protochlorophyllide. Although the mutant accumulated chlorophyllide, the last Chl precursor, we showed that it originated from dephytylation of existing Chl and not from the block in the Chl biosynthesis. The lack of de novo-produced Chl under PG depletion was accompanied by a significantly weakened biosynthesis of both monomeric and trimeric photosystem I (PSI) complexes, although the decrease in cellular content was manifested only for the trimeric form. However, our analysis of ΔpgsA mutant, which lacked trimeric PSI because of the absence of the PsaL subunit, suggested that the virtual stability of monomeric PSI is a result of disintegration of PSI trimers. Interestingly, the loss of trimeric PSI was accompanied by accumulation of monomeric PSI associated with the newly synthesized CP43 subunit of photosystem II. We conclude that the absence of PG results in the inhibition of Chl biosynthetic pathway, which impairs synthesis of PSI, despite the accumulation of chlorophyllide released from the degraded Chl proteins. Based on the knowledge about the role of PG in prokaryotes, we hypothesize that the synthesis of Chl and PSI complexes are colocated in a membrane microdomain requiring PG for integrity.

• MeSH
• bakteriální proteiny genetika   metabolismus   MeSH
• chlorofyl biosyntéza   metabolismus   MeSH
• chlorofylidy metabolismus   MeSH
• fosfatidylglyceroly genetika   metabolismus   MeSH
• fotosystém I (proteinový komplex) metabolismus   MeSH
• ligasy tvořící vazby C-O metabolismus   MeSH
• protochlorofylid metabolismus   MeSH
• světlosběrné proteinové komplexy metabolismus   MeSH
• Synechocystis genetika   metabolismus   MeSH
• transferasy pro jiné substituované fosfátové skupiny genetika   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• bakteriální proteiny MeSH
• CDP-diacylglycerol-glycerol-3-phosphate 3-phosphatidyltransferase MeSH Prohlížeč
• chlorofyl MeSH
• chlorofylidy MeSH
• chlorophyll A binding protein CP43, Cyanobacteria MeSH Prohlížeč
• chlorophyll synthetase MeSH Prohlížeč
• fosfatidylglyceroly MeSH
• fotosystém I (proteinový komplex) MeSH
• ligasy tvořící vazby C-O MeSH
• protochlorofylid MeSH
• světlosběrné proteinové komplexy MeSH
• transferasy pro jiné substituované fosfátové skupiny MeSH

In most oxygenic phototrophs, including cyanobacteria, two independent enzymes catalyze the reduction of protochlorophyllide to chlorophyllide, which is the penultimate step in chlorophyll (Chl) biosynthesis. One is light-dependent NADPH:protochlorophyllide oxidoreductase (LPOR) and the second type is dark-operative protochlorophyllide oxidoreductase (DPOR). To clarify the roles of both enzymes, we assessed synthesis and accumulation of Chl-binding proteins in mutants of cyanobacterium Synechocystis PCC 6803 that either completely lack LPOR or possess low levels of the active enzyme due to its ectopic regulatable expression. The LPOR-less mutant grew photoautotrophically in moderate light and contained a maximum of 20 % of the wild-type (WT) Chl level. Both Photosystem II (PSII) and Photosystem I (PSI) were reduced to the same degree. Accumulation of PSII was mostly limited by the synthesis of antennae CP43 and especially CP47 as indicated by the accumulation of reaction center assembly complexes. The phenotype of the LPOR-less mutant was comparable to the strain lacking DPOR that also contained <25 % of the wild-type level of PSII and PSI when cultivated under light-activated heterotrophic growth conditions. However, in the latter case, we detected no reaction center assembly complexes, indicating that synthesis was almost completely inhibited for all Chl-proteins, including the D1 and D2 proteins.

• MeSH
• 2D gelová elektroforéza MeSH
• aktivace enzymů MeSH
• bakteriální proteiny genetika   metabolismus   MeSH
• buněčná membrána enzymologie   metabolismus   MeSH
• chlorofyl biosyntéza   genetika   MeSH
• elektroforéza v polyakrylamidovém gelu MeSH
• fenotyp MeSH
• fotosystém I (proteinový komplex) genetika   metabolismus   MeSH
• fotosystém II (proteinový komplex) genetika   metabolismus   MeSH
• fototrofní procesy MeSH
• oxidoreduktasy působící na CH-CH vazby genetika   metabolismus   MeSH
• protochlorofylid metabolismus   MeSH
• regulace genové exprese enzymů * MeSH
• regulace genové exprese u rostlin MeSH
• světlo MeSH
• Synechocystis enzymologie   genetika   metabolismus   účinky záření   MeSH
• transformace genetická MeSH
• vazba proteinů MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• bakteriální proteiny MeSH
• chlorofyl MeSH
• fotosystém I (proteinový komplex) MeSH
• fotosystém II (proteinový komplex) MeSH
• oxidoreduktasy působící na CH-CH vazby MeSH
• protochlorofylid MeSH
• protochlorophyllide reductase MeSH Prohlížeč

The spectroscopic properties of photoactive (i.e. flash-transformable) and nonphotoactive protochlorophyll(ide)s (Pchl(ide)) were reinvestigated during the development of bean leaves in darkness. Two phases in the process of Pchl(ide) accumulation were apparent from quantitative measurements of pigment content: a lag phase (first week) during which photoactive Pchl(ide) accumulated faster than nonphotoactive Pchl(ide); and a fast phase (second week), showing parallel accumulation of both types of Pchl(ide). 'Flashed-minus-dark' absorbance difference spectra recorded in situ at 77 K showed that P650-655 was the predominant form of photoactive protochlorophyllide regardless of developmental stage. Quantitative analysis of energy migration processes between the Pchl(ide) forms showed the existence of energy transfer units containing a 1:8 ratio of nonphotoactive and photoactive Pchl(ide)s during development. Gaussian deconvolution of in situ 77 K fluorescence spectra indicated that the 633 nm band of nonphotoactive Pchl(ide) was made of four bands, at 625, 631, 637 and 643 nm, whose relative amplitudes only slightly changed during development. The emission band of photoactive Pchlide was also analyzed using the same method. Three components were found at 644, 652 and 657 nm. The emission band of P650-655 included the last two components, which become predominant only in fully etiolated plants. Photoactive Pchlide with an emission maximum at 653 nm was detected in the light during development of leaves of photoperiodically grown plants.

• MeSH
• Fabaceae chemie   růst a vývoj   účinky záření   MeSH
• fotobiologie MeSH
• fotoperioda MeSH
• léčivé rostliny MeSH
• listy rostlin chemie   růst a vývoj   účinky záření   MeSH
• protochlorofylid chemie   účinky záření   MeSH
• spektrofotometrie MeSH
• světlo MeSH
• tma MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• protochlorofylid MeSH