Abstract
Highly ordered arrays of intramembrane particles are observed in freeze- fractured plasma membranes of the green alga Micrasterias denticulata during the synthesis of the secondary cell wall. The observable architecture of the complex consists primarily of a precise hexagonal array of from 3 to 175 rosettes, consisting of 6 particles each, which fracture with the P-face. The complexes are observed at the ends of impressions of cellulose fibrils. The distance between rows of rosettes is equal to the center-to-center distance between parallel cellulose fibrils of the secondary wall. Correlation of the structure of the complex with the pattern of deposition indicates that the size of a given fibril is proportional to the number of rosettes engaged in its formation. Vesicles containing hexagonal arrays of rosettes are found in the cytoplasm and can be observed in the process of fusing with the plasma membrane, suggesting that the complexes are first assembled in the cytoplasm and then incorporated into the plasma membrane, where they become active in fibril formation. Single rosettes appear to be responsible for the synthesis of microfibrils during primary wall growth. Similar rosettes have now been detected in a green alga, in fern protonemata, and in higher plant cells. This structure, therefore, probably represents a significant component of the cellulose synthesizing mechanism in a large variety of plant cells.
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- Branton D., Bullivant S., Gilula N. B., Karnovsky M. J., Moor H., Mühlethaler K., Northcote D. H., Packer L., Satir B., Satir P. Freeze-etching nomenclature. Science. 1975 Oct 3;190(4209):54–56. doi: 10.1126/science.1166299. [DOI] [PubMed] [Google Scholar]
- Brown R. M., Jr, Montezinos D. Cellulose microfibrils: visualization of biosynthetic and orienting complexes in association with the plasma membrane. Proc Natl Acad Sci U S A. 1976 Jan;73(1):143–147. doi: 10.1073/pnas.73.1.143. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Brown R. M., Jr, Willison J. H., Richardson C. L. Cellulose biosynthesis in Acetobacter xylinum: visualization of the site of synthesis and direct measurement of the in vivo process. Proc Natl Acad Sci U S A. 1976 Dec;73(12):4565–4569. doi: 10.1073/pnas.73.12.4565. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Montezinos D., Brown M., Jr Surface architecture of the plant cell: biogenesis of the cell wall, with special emphasis on the role of the plasma membrane in cellulose biosynthesis. J Supramol Struct. 1976;5(3):277–290. doi: 10.1002/jss.400050303. [DOI] [PubMed] [Google Scholar]
- Mueller S. C., Brown R. M., Jr Evidence for an intramembrane component associated with a cellulose microfibril-synthesizing complex in higher plants. J Cell Biol. 1980 Feb;84(2):315–326. doi: 10.1083/jcb.84.2.315. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Mueller S. C., Brown R. M., Jr, Scott T. K. Cellulosic microfibrils: nascent stages of synthesis in a higher plant cell. Science. 1976 Nov 26;194(4268):949–951. doi: 10.1126/science.194.4268.949. [DOI] [PubMed] [Google Scholar]
- Northcote D. H., Lewis D. R. Freeze-etched surfaces of membranes and organelles in the cells of pea root tips. J Cell Sci. 1968 Jun;3(2):199–206. doi: 10.1242/jcs.3.2.199. [DOI] [PubMed] [Google Scholar]
- Robinson D. G., Preston R. D. Fine structure of swarmers of Cladophora and Chaetomorpha. I. The plasmalemma and Golgi apparatus in naked swarmers. J Cell Sci. 1971 Nov;9(3):581–601. doi: 10.1242/jcs.9.3.581. [DOI] [PubMed] [Google Scholar]
- Willison J. H., Brown R. M., Jr Cell wall structure and deposition in Glaucocystis. J Cell Biol. 1978 Apr;77(1):103–119. doi: 10.1083/jcb.77.1.103. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Zaar K. Visualization of pores (export sites) correlated with cellulose production in the envelope of the gram-negative bacterium Acetobacter xylinum. J Cell Biol. 1979 Mar;80(3):773–777. doi: 10.1083/jcb.80.3.773. [DOI] [PMC free article] [PubMed] [Google Scholar]