title: Visualization of pores (export sites) correlated with cellulose production in the envelope of the gram-negative bacterium Acetobacter xylinum.
abstract: The Gram-negative bacterium Acetobacter xylinum assembles a cellulse ribbon composed of a number of microfibrils in the longitudinal axis of its envelope. The zone of ribbon assembly was investigated by freeze-etch electron microscopy. Freeze-etching revealed, beneath the cellulose ribbons, a linear array of pores on the lipopolysaccharide membrane. These pores have a rim diameter of 120--150 A and a central hole or deepening of approximately 35 A. The axes of pore arrays closely coincide with linear arrays of 100 A particles on the E- and P-faces of the fractured lipopolysaccharide membranes. Pores and particles in the lipopolysaccharide membrane are probably congruent. The pores are hypothesized to be the export sites (penetration sites) for cellulose.
mesh_terms: D002462:Cell Membrane / Q000648:ultrastructure; D002473:Cell Wall / Q000378:metabolism / Q000648:ultrastructure; D002482:Cellulose / Q000096:biosynthesis*; D005613:Freeze Etching; D041822:Gluconacetobacter xylinus / Q000378:metabolism / Q000648:ultrastructure*; D008070:Lipopolysaccharides
chemical_list: D008070:Lipopolysaccharides; D002482:Cellulose