Morphology and Biogenesis of Cellulose and Plant Cell-Walls. Advances in Carbohydrate Chemistry and Biochemistry Volume 26. Elsevier; 1971. pp. 297-349. [DOI: 10.1016/s0065-2318(08)60370-4]

Cellulose synthesis by Acetobacter xylinum. II. Investigation into the relation between cellulose synthesis and cell envelope components

Cell envelope fractions, capable of cellulose synthesis from uridine diphosphate glucose, alpha-glucose-1-phosphate, glucose-6-phosphate and glucose, have been isolated from Acetobacter xylinum suspensions and various enzymatic properties examined. Essential enzymes were found to be distributed throughout the cell envelope region, with both inner (cytoplasmic) and outer (cell wall) membranes contributing to cellulose synthesis. The central role of UDPG in cellulose synthesis was confirmed and the results indicated that the nucleoside diphosphate sugar functions solely in the cell envelope region of whole cells. A comparison of properties of the cell envelope system with those of different preparations used by other workers, suggested that the method of cell disruption may influence substrate specificity.

Cellulose synthesis by Acetobacter xylinum. I. Low molecular weight compounds present in the region of synthesis

An analysis has been made of the low molecular weight fraction present in the region of cellulose synthesis in Acetobacter xylinum suspensions. A number of nucleic acid bases, nucleosides and nucleotides, together with alpha-glucose 1-phosphate and UDPG, were detected in various extracts of washed cells supplied with glucose. Since glucose-6-P could be detected in extracts of ultrasonically disrupted cells, but not in extracts of whole cells, it was concluded that separate pools of hexose phosphate exist in A. xylinum. Preferential release of alpha-glucose-1-P, UDPG and nucleotides was observed during ethanol and EDTA treatment of bacteria. Electron microscopic examination of treated and untreated cells revealed that extensive modification of the cell wall region occurred during such treatments. The results support the proposal that alpha-glucose-1-P, UDPG and nucleotide pools are localised in the cell envelope region, possibly in the periplasm, and that A. xylinum possesses a second permeability barrier outside the cytoplasmic membrane. Nucleic acid bases and nucleosides were observed to diffuse freely through the cell wall and accumulate in the medium, probably as the result of nucleic acid breakdown. The results imply that the effects of cell damage caused by the isolation of the bacteria from the surface pellicle of the culture medium, together with nutrient deprivation, should be considered in work using the non-proliferating system. A stydy of the variation in concentration with time of alpha-glucose-1-P and UDPG, during cellulose synthesis, indicated that both components may play an immediate role in cellulose synthesis. Glycosylated lipid compounds were detected in both cell wall extracts and supernatant fluid, but it is not certain whether these compounds are constituents of the supernatant fluid in vivo.

The formation of the fibrils in the lorica of Poteriochromonas stipitata: Tip growth, kinetics, site, orientation

The microfibrils of the lorica of Poteriochromonas stipitata Scherffel obviously are formed at the surface of the plasmalemma. They elongate unidirectionally by tip growth. On 1 μm(2) plasmalemma about 1-2×10(6) glycosidic bonds per minute are formed. In the stalk, the primary fibrils are arranged helically. They tend to fasciate; a ribbon-like fibril has the width of about 20 nm and, therewith, nearly that of a microtubule. Every primary fibril coincides precisely with a microtubule. The microtubules lie under the plasmalemma and are connected with it by cross bridges. The secondary fibrils form a more irregular network. They are mainly produced where and when microtubules are absent. They band zipper-like with each other and with the primary fibrils. It is discussed how the different structures which are involved in microfibril formation move and how the formation process is regulated. Microtubules obviously influence morphogenesis of the lorica: they participate in special orientation of microfibrils, but play no role in their synthesis and secretion.