Differential biogenesis of photosystem-II in mesophyll and bundle-sheath cells of 'malic' enzyme NADP(+)-type C4 plants. A comparative protein and RNA analysis.
We have investigated the photosystem-II organization in differentiating-bundle-sheath cells of the three malate dehydrogenase (oxaloacetate decarboxylating) (NADP+)-type C4 species maize, Sorghum and Pennisetum. Using a set of nine different antisera raised against individual subunits of photosystem-II, we demonstrate that photosystem-II components constitute a substantial part of the thylakoid membranes of young bundle-sheath chloroplasts. The abundance of subunits of the photosystem-II core, i.e. the 47-and 43-kDa chlorophyll-a-binding proteins, polypeptides D1 and D2, cytochrome b559, and the 34-kDa polypeptide, varies with the developmental state of the plant. However, the levels of the 23-kDa, 16-kDa and 10-kDa extrinsic polypeptides of the water-oxidation complex are drastically reduced in bundle-sheath chloroplasts of all three species analyzed, regardless of their state of differentiation. The reduction in protein abundance is also reflected at the transcript level: only traces of the nuclear-encoded mRNAs are found in differentiating bundle-sheath cells of Sorghum, suggesting that the transcription of these genes has been switched off. Our data are compatible with the idea that the water-oxidation complex is a prime site for initiating or maintaining the process leading to photosystem-II depletion during differentiation of bundle-sheath cells.
Institut für Entwicklungs- und Molekularbiologie der Pflanzen, Heinrich-Heine-Universität Düsseldorf, Federal Republic of Germany.
A
A
Oswald
M
M
Streubel
U
U
Ljungberg
J
J
Hermans
K
K
Eskins
P
P
Westhoff
D002734:Chlorophyll / Q000032:analysis* / Q000235:genetics; D004247:DNA / Q000032:analysis*; D004591:Electrophoresis, Polyacrylamide Gel; D015971:Gene Expression Regulation, Enzymologic; D015151:Immunoblotting; D045342:Light-Harvesting Protein Complexes; D008291:Malate Dehydrogenase / Q000032:analysis* / Q000235:genetics; D010452:Peptide Biosynthesis; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D010940:Plant Proteins / Q000032:analysis* / Q000235:genetics; D010944:Plants / Q000201:enzymology*; D012333:RNA, Messenger / Q000032:analysis*; D014158:Transcription, Genetic; D003313:Zea mays / Q000235:genetics
D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D012333:RNA, Messenger; D002734:Chlorophyll; D004247:DNA; D008291:Malate Dehydrogenase; C031917:malate dehydrogenase (oxaloacetate-decarboxylating) (NADP+)