Abstract
We have investigated the structure of the photosynthetic membrane in a mutant of barley known to lack a chlorophyll-binding protein. This protein is thought to channel excitation energy to photosystem II, and is known as the "light-harvesting chlorophyll-protein complex." Extensive stacking of thylakoids into grana occurs in both mutant and wild-type chloroplasts. Examination of membrane internal structure by freeze-fracturing indicates that only slight differences exist between the fracture faces of mutant and wild-type membranes. These differences are slight reductions in the size of particles visible on the EFs fracture face, and in the number of particles seen on the PFs fracture face. No differences can be detected between mutant and wild-type on the etched out surface of the membrane. In contrast, tetrameric particles visible on the etched inner surface of wild-type thylakoids are extremely difficult to recognize on similar surfaces of the mutant. These particles can be recognized on inner surfaces of the mutant membranes when they are organized into regular lattices, but these lattices show a much closer particle-to-particle spacing than similar lattices in wild-type membranes. Although several interpretations of these data are possible, these observations are consistent with the proposal that the light-harvesting chlorophyll-protein complex of photosystem II is bound to the tetramer (which is visible on the EFs face as a single particle) near the inner surface of the membrane. The large tetramer, which other studies have shown to span the thylakoid membrane, may represent an assembly of protein, lipid, and pigment comprising all the elements of the photosystem II reaction. A scheme is presented which illustrates one possibility for the light reaction across the photosynthetic membrane.
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Selected References
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- Anderson J. M., Levine R. P. The relationship between chlorophyll-protein complexes and chloroplast membrane polypeptides. Biochim Biophys Acta. 1974 Jul 25;357(1):118–126. doi: 10.1016/0005-2728(74)90117-0. [DOI] [PubMed] [Google Scholar]
- Anderson J. M. The molecular organization of chloroplast thylakoids. Biochim Biophys Acta. 1975 Aug 15;416(2):191–235. doi: 10.1016/0304-4173(75)90007-5. [DOI] [PubMed] [Google Scholar]
- Apel K., Bogorad L., Woodcock C. L. Chloroplast membranes of the green alga Acetabularia mediterranea. I. Isolation of the photosystem II. Biochim Biophys Acta. 1975 Jun 17;387(3):568–579. doi: 10.1016/0005-2728(75)90094-8. [DOI] [PubMed] [Google Scholar]
- Branton D., Park R. B. Subunits in chloroplast lamellae. J Ultrastruct Res. 1967 Aug;19(3):283–303. doi: 10.1016/s0022-5320(67)80222-3. [DOI] [PubMed] [Google Scholar]
- Genge S., Pilger D., Hiller R. G. The relationship between chlorophyll b and pigment-protein complex II. Biochim Biophys Acta. 1974 Apr 23;347(1):22–30. doi: 10.1016/0005-2728(74)90196-0. [DOI] [PubMed] [Google Scholar]
- Henriques F., Park R. B. Further Chemical and Morphological Characterization of Chloroplast Membranes from a Chlorophyll b-less Mutant of Hordeum vulgare. Plant Physiol. 1975 Apr;55(4):763–767. doi: 10.1104/pp.55.4.763. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Highkin H. R. CHLOROPHYLL STUDIES ON BARLEY MUTANTS. Plant Physiol. 1950 Apr;25(2):294–306. doi: 10.1104/pp.25.2.294. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Highkin H. R., Frenkel A. W. Studies of growth & metabolism of a barley mutant lacking chlorophyll b. Plant Physiol. 1962 Nov;37(6):814–820. doi: 10.1104/pp.37.6.814. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Miller K. R. A particle spanning the photosynthetic membrane. J Ultrastruct Res. 1976 Jan;54(1):159–167. doi: 10.1016/s0022-5320(76)80018-4. [DOI] [PubMed] [Google Scholar]
- Miller K. R., Bloodgood R. A., Staehelin L. A. Crystals within thylakoids: a structural analysis. J Ultrastruct Res. 1976 Jan;54(1):29–36. doi: 10.1016/s0022-5320(76)80005-6. [DOI] [PubMed] [Google Scholar]
- Miller K. R., Staehelin L. A. Analysis of the thylakoid outer surface. Coupling factor is limited to unstacked membrane regions. J Cell Biol. 1976 Jan;68(1):30–47. doi: 10.1083/jcb.68.1.30. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Miller K. R., Staehelin L. A. Fine structure of the chloroplast membranes of Euglena gracilis as revealed by freeze-cleaving and deep-etching techniques. Protoplasma. 1973;77(1):55–78. doi: 10.1007/BF01287292. [DOI] [PubMed] [Google Scholar]
- Ojakian G. K., Satir P. Particle movements in chloroplast membranes: quantitative measurements of membrane fluidity by the freeze-fracture technique. Proc Natl Acad Sci U S A. 1974 May;71(5):2052–2056. doi: 10.1073/pnas.71.5.2052. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Oleszko S., Moudrianakis E. N. The visualization of the photosynthetic coupling factor in embedded spinach chloroplasts. J Cell Biol. 1974 Dec;63(3):936–948. doi: 10.1083/jcb.63.3.936. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Park R. B., Biggins J. Quantasome: Size and Composition. Science. 1964 May 22;144(3621):1009–1011. doi: 10.1126/science.144.3621.1009. [DOI] [PubMed] [Google Scholar]
- Remy R. Resolution of chloroplast lamellar proteins by electrophoresis in polyacrylamide gels. Different patterns obtained with fractions enriched in either chlorophyll a or chlorophyll b. FEBS Lett. 1971 Apr 2;13(6):313–317. doi: 10.1016/0014-5793(71)80249-1. [DOI] [PubMed] [Google Scholar]
- Staehelin L. A. Chloroplast membrane structure. Intramembranous particles of different sizes make contact in stacked membrane regions. Biochim Biophys Acta. 1975 Oct 10;408(1):1–11. doi: 10.1016/0005-2728(75)90153-x. [DOI] [PubMed] [Google Scholar]
- Thornber J. P., Gregory R. P., Smith C. A., Bailey J. L. Studies on the nature of the chloroplast lamella. I. Preparation and some properties of two chlorophyll-protein complexes. Biochemistry. 1967 Feb;6(2):391–396. doi: 10.1021/bi00854a004. [DOI] [PubMed] [Google Scholar]
- Thornber J. P., Highkin H. R. Composition of the photosynthetic apparatus of normal barley leaves and a mutant lacking chlorophyll b. Eur J Biochem. 1974 Jan 3;41(1):109–116. doi: 10.1111/j.1432-1033.1974.tb03250.x. [DOI] [PubMed] [Google Scholar]