Comparative Studies of the Thylakoid Proteins of Mesophyll and Bundle Sheath Plastids of Zea mays (original) (raw)
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Distribution of characteristic membrane proteins in granum and stroma thylakoids
European journal of biochemistry / FEBS, 1983
Membrane fractions obtained by ultrasonication of Vicia faba thylakoids were analyzed by sodium dodecyl sulphate gel electrophoresis. The polypeptide patterns revealed a six-times-higher ratio of the apoprotein (1) of P700 chlorophyll a protein to the apoprotein (2) of one of the chlorophyll a proteins in photosystem II in the light (stroma) fraction as compared with the heavy (grana) fraction indicating different distribution of the two photosystems. Additionally, the light fraction was clearly depleted in chlorophyll a/b apoproteins 2a and 2b of the light-harvesting complex and enriched in CF1 alpha and beta subunits. In contrast to the fairly constant ratio of the CF1 subunits the ratio of chlorophyll a/b apoprotein 2a/2b differed significantly between the light and heavy fraction suggesting a different composition for light-harvesting complex in stroma and grana regions of the thylakoids.
Functional Plant Biology, 2020
A characteristic feature of C 4 plants is the differentiation of the photosynthetic leaf tissues into two distinct cell types: mesophyll (M) and bundle sheath (BS) cells. We have investigated several biochemical parameters, including pigment composition, polypeptide patterns, fluorescence at 77K, the activity of photosystems and ultrastructure of mesophyll and bundle sheath chloroplasts of maize (Zea mays L.) plants. It is shown that the BS chloroplasts have~2-fold higher chlorophyll a/b ratio than M chloroplasts, 6.15 and 3.12 respectively. The PSI apoprotein (68 kDa) was more abundant in BS than in M thylakoids. Polypeptides belonging to PSII core antenna, are in similar amounts in both types of membranes, but the 45kDa band is more intensive in M thylakoids. Polypeptides in the region of 28-24 kDa of the light-harvesting complex of PSII (LHCII) are also present in both types of chloroplasts, though their amounts are reduced in BS thylakoids. The chlorophyll fluorescence emission spectra in M cells showed the presence of three bands at 686, 695 and 735 nm characteristics of LHCII, PSII core and PSI complexes, respectively. However, in the fluorescence spectrum of agranal plastids, there are almost traces of the band at 695 nm, which belongs to the PSII core complex. The research results revealed that the photochemical activity of PSII in BS chloroplasts is~5 times less than in the chloroplasts of M cells. The highest PSI activity was found in maize BS chloroplasts.
Characterisation of stroma membranes from Zea mays L. chloroplasts
Carlsberg Research Communications, 1988
Stroma lamellae were isolated from dark-adapted maize seedling leaves by mechanical disruption of isolated, stacked thylakoids. Their chlorophyll-protein composition was analysed by non-denaturing SDS-PAGE and revealed the presence of Chla-Pl, LHCI-730, LHCI-680 and a small amount of LHCII. Also present were the chlorophyll-protein complexes Chl~-P 1', LHCI-730* and LHCII**. This is consistent with the model proposed for PSI based on detergent isolation, and confirms the presence of LHCI-680 in PSI in situ. Re-electrophoresis of the chlorophyll-protein bands under denaturing conditions, revealed three low molecular weight PSI polypeptides which were always found associated with LHCI-730. Quantitation of PSII polypeptides by immuneblot assay showed that stroma lamellae contained 30 times less than grana lamellae on a chlorophyll basis. This indicates that most of the LHCII was associated with PSI, but the oligomeric form (LHCII**) in stroma lamellae was stable only in the presence of Mg * § in contrast to LHCII** from granal membranes. This is correlated with the absence of a 26 kD LHCII polypeptide from stroma lamellae.
Differential expression of LHCII genes in mesophyll and bundle sheath cells of maize
Carlsberg Research Communications, 1986
The properties and composition of bundle sheath and mesophyl! thylakoids from maize leaves are compared. This was possible because of the isolation of large amounts of purified material obtained by enzymatic digestion of mechanically disrupted leaves. Bundle sheath thylakoids from mature leaves, lack the chlorophyll-proteins and polypeptides associated with the reaction centre ofphotosystem II. They do, however, contain significant amounts of LHCII, which transfers excitation energy to photosystem I. LHCII isolated from bundle sheath thylakoids had a different freeze-fracture ultrastructure and a different polypeptide composition from LHCII isolated from mesophyll thylakoids, indicating a differential expression of the LHCII gene family in mesophyll and bundle sheath cells of maize leaves.
The structural and functional domains of plant thylakoid membranes
The Plant Journal
In plants, the stacking of part of the photosynthetic thylakoid membrane generates two main subcompartments: the stacked grana core and unstacked stroma lamellae. However, a third distinct domain, the grana margin, has been postulated but its structural and functional identity remains elusive. Here, an optimized thylakoid fragmentation procedure combined with detailed ultrastructural, biochemical, and functional analyses reveals the distinct composition of grana margins. It is enriched with lipids, cytochrome b 6 f complex, and ATPase while depleted in photosystems and light-harvesting complexes. A quantitative method is introduced that is based on Blue Native Polyacrylamide Gel Electrophoresis (BN-PAGE) and dot immunoblotting for quantifying various photosystem II (PSII) assembly forms in different thylakoid subcompartments. The results indicate that the grana margin functions as a degradation and disassembly zone for photodamaged PSII. In contrast, the stacked grana core region contains fully assembled and functional PSII holocomplexes. The stroma lamellae, finally, contain monomeric PSII as well as a significant fraction of dimeric holocomplexes that identify this membrane area as the PSII repair zone. This structural organization and the heterogeneous PSII distribution support the idea that the stacking of thylakoid membranes leads to a division of labor that establishes distinct membrane areas with specific functions.
Purification of structurally intact grana from plants thylakoids membranes
Journal of Bioenergetics and Biomembranes, 2010
Thylakoid membranes in higher plant chloroplasts are composed by two distinct domains: stacked grana and stroma lamellae. We developed a procedure for biochemical isolation of grana membranes using mild detergent to maintain membrane structure. Pigment and polypeptide analyses of membrane preparation showed the preparations were indeed enriched in grana membranes. The method was shown to be effective in four different plant species, although with small changes in detergent concentration. Electron microscopy analyses also showed that the preparation consisted of large membrane patches with roughly round shape and diameter comparable with grana membranes in vivo. Furthermore, protein complexes distribution was shown to be maintained with respect to freeze fracture studies, demonstrating that the protocol was successful in isolating membranes close to their in vivo state.
Plant …, 2010
Chloroplast transglutaminase (chlTGase) activity is considered to play a significant role in response to a light stimulus and photo-adaptation of plants, but its precise function in the chloroplast is unclear. The characterisation, at the proteomic level, of the chlTGase interaction with thylakoid proteins and demonstration of its association with photosystem II (PSII) protein complexes was accomplished with experiments using maize thylakoid protein extracts. By means of a specific antibody designed against the C-terminal sequence of the maize TGase gene product, different chlTGase forms were immunodetected in thylakoid membrane extracts from three different stages of maize chloroplast differentiation. These bands co-localised with those of lhcb 1, 2 and 3 antenna proteins. The most significant, a 58 kDa form present in mature chloroplasts, was characterised using biochemical and proteomic approaches. Sequential fractionation of thylakoid proteins from light-induced mature chloroplasts showed that the 58 kDa form was associated with the thylakoid membrane, behaving as a soluble or peripheral membrane protein. Two-dimensional gel electrophoresis discriminated, for the first time, the 58-kDa band in two different forms, probably corresponding to the two different TGase cDNAs previously cloned. Electrophoretic separation of thylakoid proteins in native gels, followed by LC-MS mass spectrometry identification of protein complexes indicated that maize chlTGase forms part of a specific PSII protein complex, which includes LHCII, ATPase and pSbS proteins. The results are discussed in relation to the interaction between these proteins and the suggested role of the enzyme in thylakoid membrane organisation and photoprotection.
Biochimica Et Biophysica Acta-bioenergetics, 1999
Thylakoids isolated from tobacco were fragmented by sonication and the vesicles so obtained were separated by partitioning in aqueous polymer two-phase systems. By this procedure, grana vesicles were separated from stroma exposed membrane vesicles. The latter vesicles could be further fractionated by countercurrent distribution, with dextranp olyethylene glycol phase systems, and divided into two main populations, tentatively named`stroma lamellae' and`end membrane'. Both these vesicle preparations have high chlorophyll a/b ratio, high photosystem (PS) I and low PS II content, suggesting their origin from stroma exposed regions of the thylakoid. The two vesicle populations have been compared with respect to biochemical composition and photosynthetic activity. The`end membrane' has a higher chlorophyll a/b ratio (5.7 vs. 4.7), higher P700 content (4.7 vs. 3.3 mmol/mol of chlorophyll). The`end membrane' has the lowest PS II content, the ratio PS I/PS II being more than 10, as shown by EPR measurements. The PS II in both fractions is of the L-type. The decay of fluorescence is different for the two populations, the`stroma lamellae' showing a very slow decay even in the presence of K 3 Fe(CN) 6 as an acceptor. The two vesicle populations have very different surface properties: the end membranes prefer the upper phase much more than the stroma lamellae, a fact which was utilized for their separation. Arguments are presented which support the suggestion that the two vesicle populations originate from the grana end membranes and the stroma lamellae, respectively. ß