Lack of Phosphatidylglycerol Inhibits Chlorophyll Biosynthesis at Multiple Sites and Limits Chlorophyllide Reutilization in Synechocystis sp. Strain PCC 6803.
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.
Institute of Microbiology, Centre Algatech, 37981 Trebon, Czech Republic (J.Kop., J.P., V.K., J.Kom., R.S.);Faculty of Science, University of South Bohemia, 37005 Ceske Budejovice, Czech Republic (V.K., A.T., J.Kom., R.S.);Biology Centre, Institute of Parasitology, 37005 Ceske Budejovice, Czech Republic (A.T.); andInstitute of Plant Biology, Biological Research Centre, H-6701 Szeged, Hungary (M.K., Z.G.).
Jana
J
Kopečná
Institute of Microbiology, Centre Algatech, 37981 Trebon, Czech Republic (J.Kop., J.P., V.K., J.Kom., R.S.);Faculty of Science, University of South Bohemia, 37005 Ceske Budejovice, Czech Republic (V.K., A.T., J.Kom., R.S.);Biology Centre, Institute of Parasitology, 37005 Ceske Budejovice, Czech Republic (A.T.); andInstitute of Plant Biology, Biological Research Centre, H-6701 Szeged, Hungary (M.K., Z.G.).
Jan
J
Pilný
Institute of Microbiology, Centre Algatech, 37981 Trebon, Czech Republic (J.Kop., J.P., V.K., J.Kom., R.S.);Faculty of Science, University of South Bohemia, 37005 Ceske Budejovice, Czech Republic (V.K., A.T., J.Kom., R.S.);Biology Centre, Institute of Parasitology, 37005 Ceske Budejovice, Czech Republic (A.T.); andInstitute of Plant Biology, Biological Research Centre, H-6701 Szeged, Hungary (M.K., Z.G.).
Vendula
V
Krynická
Institute of Microbiology, Centre Algatech, 37981 Trebon, Czech Republic (J.Kop., J.P., V.K., J.Kom., R.S.);Faculty of Science, University of South Bohemia, 37005 Ceske Budejovice, Czech Republic (V.K., A.T., J.Kom., R.S.);Biology Centre, Institute of Parasitology, 37005 Ceske Budejovice, Czech Republic (A.T.); andInstitute of Plant Biology, Biological Research Centre, H-6701 Szeged, Hungary (M.K., Z.G.).
Aleš
http://orcid.org/0000-0002-5232-8441
A
Tomčala
Institute of Microbiology, Centre Algatech, 37981 Trebon, Czech Republic (J.Kop., J.P., V.K., J.Kom., R.S.);Faculty of Science, University of South Bohemia, 37005 Ceske Budejovice, Czech Republic (V.K., A.T., J.Kom., R.S.);Biology Centre, Institute of Parasitology, 37005 Ceske Budejovice, Czech Republic (A.T.); andInstitute of Plant Biology, Biological Research Centre, H-6701 Szeged, Hungary (M.K., Z.G.).
Mihály
M
Kis
Institute of Microbiology, Centre Algatech, 37981 Trebon, Czech Republic (J.Kop., J.P., V.K., J.Kom., R.S.);Faculty of Science, University of South Bohemia, 37005 Ceske Budejovice, Czech Republic (V.K., A.T., J.Kom., R.S.);Biology Centre, Institute of Parasitology, 37005 Ceske Budejovice, Czech Republic (A.T.); andInstitute of Plant Biology, Biological Research Centre, H-6701 Szeged, Hungary (M.K., Z.G.).
Zoltan
http://orcid.org/0000-0001-8869-6011
Z
Gombos
Institute of Microbiology, Centre Algatech, 37981 Trebon, Czech Republic (J.Kop., J.P., V.K., J.Kom., R.S.);Faculty of Science, University of South Bohemia, 37005 Ceske Budejovice, Czech Republic (V.K., A.T., J.Kom., R.S.);Biology Centre, Institute of Parasitology, 37005 Ceske Budejovice, Czech Republic (A.T.); andInstitute of Plant Biology, Biological Research Centre, H-6701 Szeged, Hungary (M.K., Z.G.).
Josef
http://orcid.org/0000-0003-4588-0382
J
Komenda
Institute of Microbiology, Centre Algatech, 37981 Trebon, Czech Republic (J.Kop., J.P., V.K., J.Kom., R.S.);Faculty of Science, University of South Bohemia, 37005 Ceske Budejovice, Czech Republic (V.K., A.T., J.Kom., R.S.);Biology Centre, Institute of Parasitology, 37005 Ceske Budejovice, Czech Republic (A.T.); andInstitute of Plant Biology, Biological Research Centre, H-6701 Szeged, Hungary (M.K., Z.G.) sobotka@alga.cz.
Roman
R
Sobotka
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D019729:Carbon-Oxygen Ligases / Q000378:metabolism; D002734:Chlorophyll / Q000096:biosynthesis* / Q000378:metabolism; D002735:Chlorophyllides / Q000378:metabolism*; D045342:Light-Harvesting Protein Complexes / Q000378:metabolism; D010715:Phosphatidylglycerols / Q000235:genetics / Q000378:metabolism*; D045331:Photosystem I Protein Complex / Q000378:metabolism; D011521:Protochlorophyllide / Q000378:metabolism; D046939:Synechocystis / Q000235:genetics / Q000378:metabolism*; D017855:Transferases (Other Substituted Phosphate Groups) / Q000235:genetics / Q000378:metabolism
D001426:Bacterial Proteins; D002735:Chlorophyllides; D045342:Light-Harvesting Protein Complexes; D010715:Phosphatidylglycerols; D045331:Photosystem I Protein Complex; D002734:Chlorophyll; C076726:chlorophyll A binding protein CP43, Cyanobacteria; D011521:Protochlorophyllide; D017855:Transferases (Other Substituted Phosphate Groups); C020676:CDP-diacylglycerol-glycerol-3-phosphate 3-phosphatidyltransferase; D019729:Carbon-Oxygen Ligases; C026901:chlorophyll synthetase