Plants terminal complexes

Terminal complex consolidation has also been reported in vascular plants as loosely aligned files of rosettes associated with secondary wall formation (13,14,34,35). Similar rosette files were also observed during primary wall formation in rapidly elongating regions of Avena coleoptiles... 

Terminal complexes have also been claimed to have been observed in freeze-fracture studies of higher-plant cells. However, at least to the inexperienced eye of this biochemist, the images seen are far less clear than those observed with the algae. Thus far, such complexes have been reported in cells of com roots,78,79 radish roots,80 and cotton... 

The 3.9 kDa band is homologous to a inner part of the PsbK gene product of liverwort and tobacco and to the N-terminal sequences of the spinach and wheat K-protein [3]. The K-protein is retained in the cyanobacterial core complex prepared by Triton X-100 while it is absent in higher plant core complex prepared by octylglucoside. 

Figure 2-1. Phytogeny of plants and algae (based on the Tree of Life website http //phylogeny. arizona.edu) showing representative terminal complex type (Tsekos 1999). Not all taxa or terminal complex types are shown. Branch lengths are arbitrary...

Hotchkiss A.T., Jr. 1989. Cellulose biosynthesis the terminal complex hypothesis and its relationship to other contemporary research topics. In Lewis N.G. and Paice M.G. (eds.) Plant Cell Wall Polymers. Biogenesis and Biodegradation. American Chemical Society, Washington, DC, pp. 232 247. 

Roberts A.W., Bushoven J., Roberts E., and Goss C. 2004. Investigating the organization and function of the cellulose-synthesizing terminal complex using Physcomitrella patens. Plant Biology... 

The enzymes have several putative transmembrane domains (TMD). This is consistent with previous microscopic and biochemical data indicating that cellulose synthase is an integral membrane protein and that cellulose biosynthesis occurs at the plasma membrane (Mueller and Brown, Jr. 1980 Ross et al. 1991 Brown, Jr. et al. 1996 Delmer 1999). Visible by electron microscopy, the enzymes form large linear terminal complexes in the plasma membrane of bacteria and many algae whereas they form hexagonal rosette structures in higher plants and some algae (Mueller and Brown, Jr. 1980 Ross et al. 1991 Kimura et al. 1999). Delmer (1999) has speculated that the transmembrane domains may create a... 

STAGES IN THE ASSEMBLY OF THE ROSETTE TERMINAL COMPLEX IN PLANTS... 

It is well known that the rosette and linear terminal complexes (TCs) can be observed by the freeze-fracture replication technique. The structures revealed by this technique are known as putative cellulose-synthesizing TCs. Kimura et al. (1999) demonstrated that TCs in vascular plants contain cellulose synthases using a novel technique of sodium dodecyl sulfate (SDS)-solubilized freeze fracture replica labeling (SDS-FRL). The localization of the cellulose synthase to the TC was accomplished almost 40 years after the hypothesis of Roelofsen (1958) in which he stated that enzyme complexes could be involved in cellulose biosynthesis. It has been more than 30 years since the discovery of the first TC by Brown, Jr. and Montezinos (1976) and in particular, 26 years after the discovery of rosette TCs in plants by Mueller and Brown, Jr. (1980). 

Figure 14-2. Comparison of SDS-FRL and conventional freeze-fracture techniques (a) freeze fracturing, (b) shadowing, (c) chromic acid treatment, (c ) Cellulase and SDS treatment, (d) antibody labeling. (Figure 2 from Itoh, T. and Kimura S. 2001. Cellulose synthases are localized in terminal complexes. Journal of Plant Research 114 483-489. Reproduced with kind permission of Springer Science and Business Media and the Botanical Society of Japan).

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